Wikipedia:Manual of Style

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The Manual of Style (often abbreviated MoS or MOS) is a style guide for Wikipedia articles. This main page contains basic principles. Subpages that set out topics in greater detail are linked in the menu to the right.

Pages in the Wikipedia project namespace, including the pages that make up the Manual of Style, other guidelines, and policies, can be searched by typing "WP:" followed by a search term in any Wikipedia search box. There is an Editor's index to Wikipedia that includes MOS pages and other pages of interest to editors.

If the Manual of Style does not specify a preferred usage, discuss the issue on the talk page.

Contents

General principles

Internal consistency

An overriding principle is that style and formatting should be consistent within a Wikipedia article, though not necessarily throughout Wikipedia as a whole. Being consistent within an article promotes clarity and cohesion. Therefore, even where the Manual of Style permits alternative usages, be consistent within an article.

Stability of articles

The Arbitration Committee has ruled that editors should not change an article from one guideline-defined style to another without a substantial reason unrelated to mere choice of style, and that revert-warring over optional styles is unacceptable.[1] Where there is disagreement over which style to use in an article, defer to the style used by the first major contributor.

Follow the sources

Many points of usage, such as the treatment of proper names, can be decided by seeing what other writers do. Unless there is some clear reason to do otherwise, follow the usage of reliable secondary sources in English on the subject; the sources for the article itself should be reliable. If the sources can be shown to be unrepresentative of current English usage, follow current English usage instead—and consult more sources.

Clarity

Writing should be clear and concise. Articles are supposed to introduce readers to topics, or remind them of what they had half-forgotten: it is not their purpose to dazzle readers with editors' learning or vocabulary. Plain English works best: avoid jargon, vague phrases, and unnecessary complexity.

Article titles, headings, and sections

Article titles[R]

This guidance applies to the titles of Wikipedia articles, not to the titles of external articles that are cited.

  • Article titles should conform to Wikipedia's Article titles, including Use English.
  • Titles should match the article contents, and should not be too narrow or too broad.
  • Titles should be nouns or noun phrases (nominal groups): Effects of the wild, not About the effects of the wild.
  • Titles should be short—preferably fewer than ten words.[2]
  • The initial letter of a title is capitalized (except in very rare cases, such as eBay). Otherwise, capital letters are used only where they would be used in a normal sentence (Funding of UNESCO projects, not Funding of UNESCO Projects).
  • Do not use a, an, or the as the first word (Economy of the Second Empire, not The economy of the Second Empire), unless by convention it is an inseparable part of a name (The Hague).
  • Avoid special characters such as the slash (/), plus sign (+), braces ({ }), and square brackets ([ ]); use and instead of an ampersand (&), unless the ampersand is an accepted part of a name (Emerson, Lake & Palmer).
  • The final visible character of a title should not be a punctuation mark, unless the punctuation is part of a name (Saint-Louis-du-Ha! Ha!), or an abbreviation is used (Inverness City F.C.), or a closing round bracket or quote mark is needed (John Palmer (schooner)).

This guidance also applies to Section headings, below.

Section headings

Shortcuts:
WP:HEAD
WP:MOSHEAD
WP:Headings
MOS:HEAD
See also the guidance in Article titles immediately above, which applies to both article titles and section headings.
  • Headings provide an overview in the table of contents and allow readers to navigate through the text more easily.
  • Change a heading only after careful consideration, because this will break section links to it within the same article and from other articles. If changing a heading, try to locate and fix broken links.
  • Section names should preferably be unique within a page; this applies even for the names of subsections. The disadvantages of duplication are that:
    • section names that are not unique produce nonstandard XHTML;[3]
    • after editing, the display can arrive at the wrong section; see also below; and
    • the automatic edit summary on editing a section with a non-unique name is ambiguous.
  • Section names should not normally contain links, especially ones that link only part of the heading; they will cause accessibility problems.
  • Section names should not explicitly refer to the subject of the article, or to higher-level headings, unless doing so is shorter or clearer. For example, Early life is preferable to His early life when his refers to the subject of the article; headings can be assumed to be about the subject unless otherwise indicated.
  • Capitalize the first letter of the first word and any proper nouns in headings, but leave the rest in lower case (Rules and regulations, not Rules and Regulations).
  • Spaced or unspaced multiple equal signs are the style markup for headings. The triple apostrophes (''') that make words appear in boldface are not used in headings. The nesting hierarchy for headings is as follows:
    • the automatically generated top-level heading of a page is H1, which gives the article title;
    • primary headings are then ==H2==, followed by ===H3===, ====H4====, and so on.
  • Spaces between the == and the heading text are optional (==H2== is equivalent to == H2 ==). These extra spaces will not affect the appearance of the heading, except in the edit window. (Some common bots, however, are programmed to remove them.) While editing, the spaces afford greater compatibility with browser spell checking software.
  • A blank line below the heading is optional; but do include one blank line above the heading, for readability in the edit window. (Only two or more blank lines above or below will add more white space in the public appearance of the page.)

Main article link

If the topic of a section is also covered in a dedicated article, then this should be marked by inserting {{main|Article name}} directly beneath the section heading.

Section management

Shortcut:
MOS:SECTIONS
  • When linking to a section of an article, go to that section and leave an editor's note to inform others that the section's title is linked. List the names of the linking articles, so that if the title is altered, others can fix the links without having to perform exhaustive searches. For example:

==Evolutionary implications<!--This section is linked from [[Richard Dawkins]] and [[Daniel Dennett]]-->==

  • As well, consider a preemptive measure to minimize link corruption when the text of a heading changes: insert an {{anchor}} with the old name, which will then still work as an alternative link to that section. For example:

==New section name{{anchor | Evolutionary implications}}<!-- This section is linked from [[Richard Dawkins]] and [[Daniel Dennett]] -->==

  • As explained in more detail at Wikipedia:Layout#Standard appendices and descriptions, optional appendix sections containing the following information may appear after the body of the article, in the following order: (a) a list of books or other works created by the subject of the article; (b) a list of internal links to related Wikipedia articles; (c) notes and references; (d) a list of recommended relevant books, articles, or other publications that have not been used as sources; and (e) a list of recommended relevant websites that have not been used as sources and do not appear in the earlier appendix sections.

Capital letters

There are differences between the major varieties of English in the use of capitals (majuscule or uppercase letters). Where this is an issue, the rules and conventions of the cultural and linguistic context apply. As for spelling, maintain consistency within an article.

Do not use capitals letters for emphasis on Wikipedia. Where wording alone cannot provide the emphasis, use italics.

Incorrect:    Contrary to popular belief, aardvarks are Not the same as anteaters.
Incorrect: Contrary to popular belief, aardvarks are NOT the same as anteaters.
Correct: Contrary to popular belief, aardvarks are not the same as anteaters.

Use of "The" mid-sentence

In general, do not capitalize the definite article in the middle of a sentence. However, there are idiomatic exceptions, including most titles of works of art, which should be quoted exactly. Common usage should be followed for particular cases. As usual, it is a good idea to consult the sources of the article.

Incorrect  (generic):    There was an article about The United Kingdom in yesterday's newspaper.
Correct (generic): There was an article about the United Kingdom in yesterday's newspaper.
Incorrect  (title):    J.R.R. Tolkien wrote the Lord of the Rings.
Correct (title): J.R.R. Tolkien wrote The Lord of the Rings.
Correct (title): Homer wrote the Odyssey.
Incorrect (exception): There are two seaside resorts in the Hague.
Correct (exception): There are two seaside resorts in The Hague.

Titles of people

  • When used generically, words such as president, king, and emperor are in lower case (De Gaulle was a French president; Louis XVI was a French king; Three prime ministers attended the conference).
  • When used as parts of a title such words begin with a capital letter (President Obama, not president Obama). Standard or commonly used names of an office are treated as proper nouns (The British Prime Minister is Gordon Brown; Hirohito was Emperor of Japan; Louis XVI was King of France). Royal styles are capitalized (Her Majesty; His Highness); exceptions may apply for particular offices.

Religions, deities, philosophies, doctrines, and their adherents

  • Religions, sects, and churches and their followers (in noun or adjective form) start with a capital letter. Generally, the is not capitalized before such names (the Shī‘a, not The Shī‘a). (However, see also the style guide and naming convention for the Latter Day Saint movement.)
  • Religious texts (scriptures) are capitalized but often not italicized (the Bhagavad Gita, the Qur’an, the Talmud, the Granth Sahib, the Bible). When the is used, it is not capitalized. Some derived adjectives are capitalized by convention, some are not (normally biblical but Koranic, for example); if unsure, check a dictionary appropriate to the topic, and be consistent within an article.
  • Honorifics for deities, including proper nouns and titles, start with a capital letter (God, Allah, the Lord, the Supreme Being, the Great Spirit, the Horned One, Bhagavan). The article the is not capitalized unless it is formally a part of the name of the deity. The same is true when referring to major religious figures and figures from mythology by titles or terms of respect (the Prophet, the Messiah, the Virgin). Common nouns denoting deities or religious figures are not capitalized (the Romans worshipped many gods; many Anglo-Saxons worshipped the god Wotan; Jesus and Muhammad are both considered prophets in Islam; biblical scholars dispute whether Mary was a virgin for her entire life; her husband was her muse, but the nine Muses).
  • Pronouns and possessives referring to figures of veneration are not capitalized in Wikipedia articles, even when they traditionally are in a religion's scriptures. They are left capitalized when directly quoting scriptures or any other texts that capitalize them.
  • Broad categories of mythical or legendary creatures do not start with uppercase capital letters (elf, fairy, nymph, unicorn, angel), although in derived works of fantasy, such as the novels of J.R.R. Tolkien and real-time strategy video games, initial capitals are sometimes used to indicate that the beings are regarded as forming a culture or a race in their fictional universes. Names or titles of individual creatures are capitalized (the Minotaur, the Pegasus) as are those of groups whose name and membership are fixed (the Magi or the Three Wise Men, the Cherubim). As with terms for deities, generalized references are not capitalized (the priests of this sect were called magi by some; several wise men were consulted; cherub-like).
  • Spiritual or religious events are likewise capitalized only when they are terms referring to specific incidents or periods (the Great Flood and the Exodus; but annual flooding and an exodus of refugees).
  • Philosophies, theories, movements, and doctrines do not begin with a capital letter unless the name derives from a proper noun (capitalism versus Marxism) or has become a proper noun (lowercase republican refers to a system of political thought; uppercase Republican refers to one of several specific political parties or ideologies, such as the US Republican Party or Irish Republicanism). Use lower case for doctrinal topics or canonical religious ideas (as distinguished from specific events), even if they are capitalized by some religious adherents (virgin birth, original sin, transubstantiation).
  • Platonic or transcendent ideals are capitalized (Truth, the Good), but only within the context of philosophical doctrine; used more broadly, they are in lower case (Superman represents American ideals of truth and justice). Use capitals for personifications represented in art (The guidebook mentioned statues of Justice and Liberty).

Calendar items

  • Months, days of the week, and holidays start with a capital letter (June, Monday; the Fourth of July only for the US Independence Day, otherwise July 4 or 4 July).
  • Seasons are in lowercase (this summer was very hot; the winter solstice occurs about December 22; I have spring fever), except in personifications or in proper names for periods or events (I think Spring is showing her colors; Old Man Winter; The team had great success on the Spring Circuit).

Animals, plants, and other organisms

Scientific names for genera and species are italicized, with a capital initial letter for the genus but no capital for the species; for more detailed guidelines on titles with taxonomic terms, see Wikipedia:WikiProject Tree of Life#Article titles (The tulip tree is Liriodendron tulipifera; All modern humans are Homo sapiens. Taxonomic groups higher than genus are given with an initial capital and are not in italics; for example, gulls are in the family Laridae, and we are in the family Hominidae.

Common (vernacular) names of flora and fauna should be written in lower case (oak, lion). There are some exceptions:

  1. Where the vernacular name contains a proper noun, such as the name of a person or place, that proper noun should be capitalized (The Amur tiger may have a range of over 500 square kilometres; The Roosevelt elk is a subspecies of Cervus canadensis).
  2. For particular groups of organisms, there are particular rules of capitalization based on current and historic usage among those who study the organisms; for example, official common names of birds.
  3. In a very few cases, a set of officially established common names is recognized only within a country or a geographic region. Those common names may be capitalized according to local custom, but not all editors will have access to the references needed to support these names; in such cases, using the general recommendation is also acceptable.

A redirect from an alternative capitalization should be created where it is used in an article title.

In articles that cover two or more taxonomic groups, a consistent style of capitalization should be used for species names. This could involve the use of:

  • scientific names throughout (often appropriate for specialist articles);
  • title case for common names of species throughout, and lower case for common names of groups of species (the Golden Eagle is a relatively large eagle; see WP:BIRDS); or
  • lower-case initial letters for common names, which may work well for non-specialist articles that happen to refer to different taxonomic groups.

Celestial bodies

  • When used generally, the words sun, earth, and moon do not take capitals (The sun was peeking over the mountain top; The greatest cobalt deposit on earth.), except for when the entities are personified (Sol Invictus ("Unconquered Sun") was the Roman sun god) or when the term refers to the names of specific astronomical bodies (The Moon orbits the Earth; but Io is a moon of Jupiter).
  • Names of planets, moons, asteroids, comets, stars, constellations, and galaxies are proper nouns, and therefore capitalized (The planet Mars can be seen tonight in the constellation Gemini, near the star Pollux; Halley's Comet is the most famous of the periodic comets; The Andromeda Galaxy is a spiral galaxy). The first letter of every word in such a name is capitalized (Alpha Centauri and not Alpha centauri; Milky Way, not Milky way).

Directions and regions

  • Directions such as north do not take capitals, except as parts of names. The same is true for their related forms (We took the northern road; but It was referred to by locals as the Great North Road). Composite directions may or may not be hyphenated, depending on the general style adopted in the article (Southeast Asia and northwest in American English; but South-East Asia and north-west in British English).
  • Names of regions are capitalized, including informal conventional names (Southern California; the Western Desert; Old Cow Hill); and similarly with persons referred to by place of origin or residence (He was the only Southerner among many Northerners). If uncertain whether to capitalize, do not.

Institutions

  • Names of institutions (the University of Sydney; George Brown College) are proper nouns and require capitals. The word the at the start of a title is usually uncapitalized, but the institution's own usage should be followed (a degree from the University of Sydney; but football players at The Ohio State University).
  • Generic words for institutions (university, college, hospital, high school) do not take capitals:
Incorrect  (generic):    The University offers programs in arts and sciences.
Correct (generic): The university offers ...
Correct (title): The University of Delhi offers ...
  • Political or geographical units, such as cities, towns, and countries, follow the same rules: the names of specific cities, towns, countries, and the like are proper nouns and require capitals; but generic words for types of government bodies do not take capitals. Sometimes, the full official name of a body is not needed.
Incorrect  (generic):    The City has a population of 55,967.
Correct (generic): The city has ...
Correct (title): The City of Smithville has ...
Correct (type unspecified): Smithville has ...

Acronyms and abbreviations

Write out both the full version and the abbreviation at first occurrence
When introducing a new name in an article, use the full name on its first occurrence, followed by the abbreviated form in round brackets. This clears the way for later use of the abbreviation alone (the New Democratic Party (NDP) won the 1990 Ontario election with a significant majority, at the first mention of the New Democratic Party; and the NDP quickly became unpopular with the voters, at a subsequent mention).
Do not apply initial capitals in the full name just because capitals are about to be used in the abbreviation.
Incorrect  (not a name):    We used Digital Scanning (DS) technology
Correct:   We used digital scanning (DS) technology
Correct: (name): produced by the British Broadcasting Corporation (BBC)
If the full term is already in round brackets, use a comma and or to indicate the abbreviation.
Correct                 They first debated the issue in 1992 (at a convention of the New Democratic Party, or NDP)
Plural and possessive forms
Acronyms and initialisms, like other nouns, become plurals by adding -s or -es (they produced three CD-ROMs in the first year; the laptops were produced with three different BIOSes in 2006). As with other nouns, no apostrophe is used unless the form is a possessive.
Periods (full stops) and spaces
The letters in an acronym or an initialism are generally not separated by full stops (periods) or blank spaces (GNP, NORAD, OBE, GmbH). Periods and spaces that were traditionally required have now dropped out of usage (PhD is now preferred over Ph.D. and Ph. D.). Full stops are not used in units of measurement; see Wikipedia:Manual of Style (dates and numbers) for more information.
Abbreviations formed by truncation (Hon. for Honorable), compression (cmte. for committee), or contraction (Dr. for Doctor) may or may not be closed with a period; a consistent style should be maintained within an article. A period is more usual in American usage (Dr. Smith of 42 St. Joseph St.); no full stop is commonly preferred in British and other usage (Dr Smith of 42 St Joseph St, although one or other St might take a period, in such a case). British and some other authorities prefer to drop the stop from truncated and compressed abbreviations generally (XYZ Corp; ABC Ltd), a practice favored in science writing. Regardless of punctuation, any separate words in such abbreviations are spaced (op. cit. or op cit; not op.cit. or opcit).
US and U.S.
In American English, U.S. (with periods) is more accepted as the standard abbreviation for United States; US (without periods) is more accepted in other national forms of English, and is becoming increasingly common in American English. In longer abbreviations incorporating the country's initials (USN, USAF), periods are not used. When the United States is mentioned with one or more other countries in the same sentence, U.S. or US may be too informal, especially at the first mention (France and the United States, not France and the U.S.). For consistency in an article, if the abbreviated form for the United States appears alongside other abbreviated country names, avoid periods throughout; never add full stops to the other abbreviations (the US, the UK, and the PRC, not the U.S., the U.K., and the P.R.C.). Do not use the spaced U. S., nor the archaic U.S. of A., except when quoting. Do not use U.S.A. or USA, except in a quotation or as part of a proper name (Team USA).
Do not use unwarranted abbreviations
Avoid abbreviations when they might confuse the reader, interrupt the flow, or appear informal or lazy. For example, do not use approx. for approximate or approximately, except to reduce the width of an infobox or a table of data, or in a technical passage in which the term occurs many times.
See also Wikipedia:Manual of Style (dates and numbers) for when to abbreviate units of measurement.
Do not invent abbreviations or acronyms
Generally avoid making up new abbreviations, especially acronyms (World Union of Billiards is good as a translation of Union Mondiale de Billard, but neither it nor the reduction WUB is used by the organization; so use the original name and its official abbreviation, UMB). If in a wide table of data it is necessary to abbreviate a heading, use widely recognized initialisms (for United States gross national product use US and GNP spaced together, with a link to appropriate articles if the terms are not already explained: US GNP; do not use the made-up initialism USGNP).
HTML elements
The software that Wikipedia runs on does not support the HTML phrase element <acronym> (see Mediazilla:671). The <abbr> element can be used instead: <abbr title="HyperText Markup Language">HTML</abbr> generates HTML.

Italics

Emphasis
Italics may be used sparingly to emphasize words in sentences (whereas boldface is normally not used for this purpose). Generally, the more highlighting in an article, the less its effectiveness.
Use italics when introducing terms, or distinguishing among them (The enamel organ is composed of the outer enamel epithelium, inner enamel epithelium, stellate reticulum, and stratum intermedium).
Titles
Use italics for the titles of works of literature and art, such as books, paintings, films (feature-length), television series, and musical albums. The titles of articles, chapters, songs, television episodes, short films, and other short works are not italicized, but are enclosed in double quotation marks.
Italics are not used for major revered religious works (the Bible, the Qur'an, the Talmud).
Words as words
Use italics when mentioning a word or letter (see Use–mention distinction) or a string of words up to one full sentence (the term panning is derived from panorama, a word coined in 1787; the most commonly used letter in English is e). When a whole sentence is mentioned, quotation marks may be used instead, with consistency (The preposition in She sat on the chair is on; or The preposition in "She sat on the chair" is "on"). Mentioning (to discuss such features as grammar, wording, and punctuation) is different from quoting (in which something is usually expressed on behalf of a quoted source).
Foreign words
Use italics for phrases in other languages and for isolated foreign words that are not common in everyday English. Proper names (such as place names) in other languages, however, are not usually italicized.
Quotations in italics
For quotations, use only quotation marks (for short quotations) or block quoting (for long ones), not italics. (See Quotations below.) This means that (1) a quotation is not italicized inside quotation marks or a block quote just because it is a quotation, and (2) italics are no substitute for proper quotation formatting.
Italics within quotations
Use italics within quotations if they are already in the source material. When adding italics on Wikipedia, add an editorial note [emphasis added] after the quotation.

"Now cracks a noble heart. Good night sweet prince: And flights of angels sing thee to thy rest" [emphasis added].

If the source has used italics (or some other styling) for emphasis and this is not otherwise evident, the editorial note [emphasis in original] should appear after the quotation.
Effect on nearby punctuation
Italicize only the elements of the sentence affected by the emphasis. Do not italicize surrounding punctuation.
Incorrect:    What are we to make of that?
Correct: What are we to make of that?
      (Note the difference between ? and ?. The question mark applies to the whole sentence, not just to the emphasized that.)
Correct: Four of Patrick White's most famous novels are A Fringe of Leaves, The Aunt's Story, Voss, and The Tree of Man.
(The commas, period, and the word and are not italicized.)
Italicized links
The italics markup must be outside the link markup, or the link will not work; however, internal italicization can be used in piped links.
Incorrect:    The opera [[''Turandot'']] is his best.
Correct: The opera ''[[Turandot]]'' is his best.
Correct: The [[USS Adder (SS-3)|USS ''Adder'' (SS-3)]] was a submarine.

Non-breaking spaces

  • A non-breaking space (also known as a hard space) is recommended to prevent the end-of-line displacement of elements that could be awkward at the beginning of a new line:
    • in many compound expressions in which figures and abbreviations or symbols are separated by a space (17 kg, AD 565, 2:50 pm written as 17&nbsp;kg, AD&nbsp;565, 2:50&nbsp;pm), including scientific names of species where the genus is abbreviated (C. elegans);
    • in other places where displacement might be disruptive to the reader (£11 billion, 5° 24′ 21.12″ N, Boeing 747, and the first two elements in 7 World Trade Center).
  • A hard space can be produced with the HTML code &nbsp; instead of the space bar: 19&nbsp;kg yields a non-breaking 19 kg.
  • Hard spaces can also be produced by using the {{nowrap}} template: {{nowrap|8 sq ft}} produces a non-breaking 8 sq ft. This is especially useful for short constructions requiring two or more hard spaces, as in the preceding example. Template {{nowrap}} has the disadvantage that if the enclosed text starts or ends with a space, these spaces are forced outside in the resulting HTML, and unpredicted breaks may occur. If &nbsp; occurs right before {{nowrap}}, or at the start of text within {{nowrap}}, some browsers allow a break at that point.
  • Unlike normal spaces, multiple hard spaces are not compressed by browsers into a single space.

Quotations

Shortcuts:
WP:MOSQUOTE
MOS:QUOTE
Minimal change
Preserve the original text, spelling, and punctuation. Where there is a good reason to make a change, insert an explanation within square brackets (for example, [her father] replacing him, where the context explaining him is omitted in the quotation). If there is a significant error in the original statement, use [sic], or the template {{sic}} (which produces [sic]), to show that the error was not made in transcription. Trivial spelling or typographical errors should be silently corrected (for example, correct ommission to omission, harasssment to harassment—unless the slip is textually important).
Use ellipses to indicate omissions from quoted text. Legitimate omissions include extraneous, irrelevant, or parenthetical words, and unintelligible or guttural speech (umm, and hmm). Do not omit text where doing so would remove essential context or alter the meaning of the text.
Allowable typographical changes
Although the requirement of minimal change is strict, a few purely typographical elements of quoted text should be conformed to English Wikipedia's conventions without comment. This practice of conforming typographical styling to a publication's own "house style" is universal. Allowable typographical alterations include these:
  • Styling of dashes—use the style chosen for the article: unspaced em dash or spaced en dash. (See Dashes, below.)
  • Styling of apostrophes and quotation marks: they should all be straight, not curly. See Quotation marks below. In quoting foreign-language text, replace foreign typographical elements such as guillemets (« ») with their English-language equivalents. Replace guillemets with straight quotation marks, and so on.
  • Spaces before punctuation such as periods and colons: these should be removed as alien to modern English-language publishing.
  • Some text styling should be altered. Of course the typeface will be automatically standardized; but generally preserve bold and italics (see Italics, above). Where the source is an old typewritten document such as an academic dissertation, underlining is almost certainly used to represent italics, and should be changed to italics as it would be by any book publisher.
  • Disused glyphs and ligatures in old texts may be modified according to modern practice (see Ampersand, below).
  • If an entire sentence is quoted in such a way that it becomes a grammatical part of the larger sentence, the first letter loses its capitalization (It turned out to be true that "a penny saved is a penny earned").
Quotations within quotations
When a quotation includes another quotation (and so on), start with double quote marks outermost, and, working inward, alternate single with double quote marks ("She disputed his statement that 'Voltaire never said "I disapprove of what you say, but I will defend to the death your right to say it."'", with three levels of quotation). Adjacent quote marks, as at the end of that last example, can be difficult to read ("'") unless kerned apart slightly with CSS; the {{" '}}, {{' "}} and {{" ' "}} templates will accomplish this; the example above is achieved by typing this: ... your right to say it.{{" ' "}}.
Attribution
The author of a quote of a full sentence or more should be named; this is done in the main text and not in a footnote. However, attribution is unnecessary with quotations that are clearly from the person discussed in the article or section. When preceding a quotation with its attribution, avoid characterizing it in a biased manner.
Linking
As much as possible, avoid linking from within quotes, which may clutter the quotation, violate the principle of leaving quotations unchanged, and mislead or confuse the reader.
Block quotations
Format a long quote (more than four lines, or consisting of more than one paragraph, regardless of number of lines) as a block quotation, which Wikimedia's software will indent from both margins. Do not enclose block quotations in quotation marks (and especially avoid decorative quotation marks in normal use, such as those provided by the {{cquote}} template, which are reserved for pull quotes). Block quotations can be enclosed between a pair of <blockquote>...</blockquote> HTML tags; or use {{quotation}} or {{quote}}.

Wikipedia's MediaWiki software does not render multiple paragraphs inside a <blockquote> simply by spacing the paragraphs apart with blank lines. A workaround is to enclose each block-quoted paragraph in its own <p>...</p> element:

<blockquote>
<p>And bring us a lot of horilka, but not of that fancy kind with raisins,
or with any other such things—bring us horilka of the purest kind, give us that
demon drink that makes us merry, playful and wild!</p>
 
<p>—[[Nikolai Gogol]], ''[[Taras Bulba]]''</p>
</blockquote>

This will result in the following, indented on both sides (it may also be in a smaller font, depending on browser software):

And bring us a lot of horilka, but not of that fancy kind with raisins, or with any other such things—bring us horilka of the purest kind, give us that demon drink that makes us merry, playful and wild!

Nikolai Gogol, Taras Bulba

The {{quote}} template provides the same semantic HTML formatting, as well as a workaround for the paragraph spacing bug and a pre-formatted attribution line:

{{quote|And bring us a lot of horilka, but not of that fancy kind with raisins,
or with any other such things—bring us horilka of the purest kind, give us that
demon drink that makes us merry, playful and wild!|[[Nikolai Gogol]]|''[[Taras Bulba]]''}}

This will result in:

And bring us a lot of horilka, but not of that fancy kind with raisins,

or with any other such things—bring us horilka of the purest kind, give us that demon drink that makes us merry, playful and wild!

Punctuation

Shortcuts:
WP:PUNC
WP:PUNCT

Apostrophes

  • Consistent use of the straight (or typewriter) apostrophe ( ' ) is recommended, as opposed to the curly (or typographic) apostrophe (  ). For details and reasons, see Quotation marks, below.
  • For the possessive apostrophe, see the summary of usage issues at Possessives, below.
  • Foreign characters that resemble apostrophes, such as transliterated Arabic ayin ( ʿ ) and alif ( ʾ ), are represented by their correct Unicode characters (that is, U+02BF MODIFIER LETTER LEFT HALF RING and U+02BE MODIFIER LETTER RIGHT HALF RING respectively), despite possible display problems. If this is not feasible, use a straight apostrophe instead.
  • For a thorough treatment of all uses of the apostrophe (possessive, elision, formation of certain plurals, specific foreign-language issues) see the article Apostrophe.

Quotation marks[R]

The term quotation in the material below also includes other uses of quotation marks such as those for titles of songs, chapters, episodes, unattributable aphorisms, literal strings, "scare-quoted" passages, and constructed examples.

Double or single

Enclose quotations with double quotation marks (Bob said, "Jim ate the apple."). Enclose quotations within quotations with single quotation marks (Bob said, "Did Jim say 'I ate the apple' after he left?").

Wikipedia prefers double quotation marks because some search engines cannot find quotations within single quotation marks, like 'I ate the apple'. (Wikipedia's search facility will only find such an expression if the search string is also within single quotation marks.) In addition, double quotation marks are harder to confuse with apostrophes.

Article openings
When the title of an article appearing in the lead paragraph requires quotation marks (for example, the title of a song or poem), the quotation marks should not be in boldface, as they are not part of the title:
Correct: "Jabberwocky" is a nonsense poem by Lewis Carroll.
Block quotes
As already noted above, we use quotation marks or block quotes (not both) to distinguish long quotations from other text. Multiparagraph quotations are always block-quoted. The quotations must be precise and exactly as in the source (except for certain allowable typographical changes, also noted above). The source should be cited clearly and precisely to enable readers to locate the text in question, and to quote it accurately themselves from Wikipedia.
Quotation characters
Do not use Grave and acute accents or backticks (`text´) as quotation marks (or as apostrophes).
There have traditionally been two styles concerning the look of the quotation marks (that is, the glyphs, displayed with emphasis here, for clarity):
  • Typewriter or straight style: "text", 'text'. Recommended.
  • Typographic or curly style: text, text. Not recommended.
The exclusive use of straight quotation marks and apostrophes (see preceding section) is recommended. They are easier to type in reliably, and to edit. Mixed use interferes with some searches, such as those using the browser's search facility (a search for Alzheimer's disease could fail to find Alzheimer’s disease and vice versa). Furthermore, HTML elements (such as <ref name="xxx"/>) may not always work if curly quotation marks are used.
Whenever quotation marks or apostrophes appear in article titles, make a redirect from the same title but using the alternative glyphs.

Punctuation inside or outside

Shortcut:
WP:LP

On Wikipedia, place all punctuation marks inside the quotation marks if they are part of the quoted material and outside if they are not. This practice is sometimes referred to as logical punctuation. It is used on Wikipedia in accordance with the principle of minimal change. This punctuation system does not require placing final periods and commas outside the quotation marks all the time but rather maintaining their original positions in (or absence from) the quoted material.

Correct: Arthur said, "The situation is deplorable and unacceptable."
(The period is known to be in the source.)
Correct: Arthur said that the situation was "deplorable".
(The period is either known not to be in the source, its presence in the source is uncertain, or its coverage within the quotation is considered unnecessary.)
Correct: Martha asked, "Are you coming?"
(The question mark belongs inside because the quoted text itself was a question.)
Correct: Did Martha say, "Come with me"?
(The very quote is being questioned, so the question mark belongs outside; any punctuation at the end of the original quote is omitted.)
When quoting a sentence fragment that ends in a period, some judgment is required: if the fragment communicates a complete sentence, the period can be placed inside. The period should be omitted if the quotation is in the middle of a sentence.
Correct: Martha said, "Come with me", and they did.
If the sequence of juxtaposed punctuation marks seems distracting or untidy, try an acceptable alternative.
Correct: Martha said, "Come with me" (and they did).

Brackets and parentheses

These rules apply to both round brackets ( ( ) ), often called parentheses, and square brackets ( [ ] ).

If a sentence contains a bracketed phrase, place the sentence punctuation outside the brackets (as shown here). However, where one or more sentences are wholly inside brackets, place their punctuation inside the brackets (see Sentences and brackets below). There should be no space next to the inner side of a bracket. An opening bracket should be preceded by a space, except in unusual cases; for example, when it is preceded by an opening quotation mark, another opening bracket, or a portion of a word:

He rose to address the meeting: "(Ahem) ... Ladies and gentlemen, welcome!"

Only the royal characters in the play ([Prince] Hamlet and his family) habitually speak in blank verse.

We journeyed on the Inter[continental].

There should be a space after a closing bracket, except perhaps where a punctuation mark other than an apostrophe or a dash follows, and in unusual cases similar to those listed for opening brackets.

If sets of brackets are nested, use different types for adjacent levels of nesting; for two levels, it is customary to have square brackets appear within round brackets. This is often a sign of excessively convoluted expression; it is often better to recast, linking the thoughts with commas, semicolons, colons, or dashes.

Avoid adjacent sets of brackets. Either put the parenthetic phrases in one set separated by commas, or rewrite the sentence:

Incorrect:    Nikifor Grigoriev (c. 1885–1919) (also known as Matviy Hryhoriyiv) was a Ukrainian insurgent leader.
Correct: Nikifor Grigoriev (c. 1885–1919), also known as Matviy Hryhoriyiv, was a Ukrainian insurgent leader.
Correct: Nikifor Grigoriev (c. 1885–1919) was a Ukrainian insurgent leader. He was also known as Matviy Hryhoriyiv.

Square brackets are used to indicate editorial replacements and insertions within quotations, though this should never alter the intended meaning. They serve three main purposes:

  • To clarify. (She attended [secondary] school, where this was the intended meaning, but the type of school was unstated in the original sentence.)
  • To reduce the size of a quotation. (X contains Y, and under certain circumstances, X may contain Z as well may be reduced to X contains Y [and sometimes Z].) When an ellipsis (...) is used to indicate that material is removed from a direct quotation, it should not normally be bracketed (see Ellipses, below).
  • To make the grammar work. (Referring to someone's statement "I hate to do laundry", one could properly write: She "hate[s] to do laundry".)

Sentences and brackets

  • If any sentence includes material that is enclosed in square or round brackets, it still must end—with a period, or a question or exclamation mark—after those brackets. This principle applies no matter what punctuation is used within the brackets:
She refused all requests (except for basics such as food, medicine, etc.).
  • However, if the entire sentence is within brackets, the closing punctuation falls within the brackets. (This sentence is an example.) This does not apply to matter that is added (or modified editorially) at the beginning of a sentence for clarity, which is usually in square brackets:
"[Principal Skinner] already told me that", he objected.
That is preferable to this, which is potentially ambiguous:
"He already told me that", he objected.
But even here consider an addition rather than a replacement of text:
"He [Principal Skinner] already told me that", he objected.
  • A sentence that occurs within brackets in the course of another sentence does not generally have its first word capitalized just because it starts a sentence. The enclosed sentence may have a question mark or exclamation mark added, but not a period. See the indented example above, and also:
Alexander then conquered (who would have believed it?) most of the known world.
Clare demanded that he drive (she knew he hated driving) to the supermarket.
It is often clearer to separate the thoughts into separate sentences or clauses:
Alexander then conquered most of the known world. Who would have believed it?
Clare demanded that he drive to the supermarket; she knew he hated driving.

Brackets and linking

If the text of a link needs to contain one or more square brackets, "escape" these using <nowiki></nowiki> tags or the appropriate numerical character reference.

He said "I spoke to [[John Doe|John &#91;Doe&#93;]] that morning."

He said "I spoke to John [Doe] that morning."

*Branwen, Gwern (2009). [http://lists.wikimedia.org/pipermail/wikien-l/2009-November/105182.html <nowiki>[WikiEN-l]</nowiki> Chinese start caring about copyright].

If a URL itself contains square brackets, the wiki-text should use the url-encoded form: something.php?query=%5Bxxx%5Dxxx&whatever=else rather than query=[xxx]bar to avoid truncating the link text after "xxx". Of course, this issue only arises for external links as MediaWiki software forbids square brackets in page titles.

Ellipses

Shortcuts:
WP:ELLIPSES
WP:ELLIPSIS
MOS:ELLIPSIS

An ellipsis (plural ellipses) is an omission of material from quoted text; or some other omission, perhaps of the end of a sentence, often used in a printed record of conversation. The ellipsis is represented by ellipsis points: a set of three dots.

Style
Ellipsis points, or ellipses, have traditionally been implemented in three ways:
  • Three unspaced periods (...). This is the easiest way, and gives a predictable appearance in HTML. Recommended.
  • Pre-composed ellipsis character (); generated with the &hellip; character entity, or as a literal "…". This is harder to input and edit, and too small in some fonts. Not recommended.
  • Three spaced periods (. . .). This is an older style that is unnecessarily wide and requires non-breaking spaces to keep it from breaking at the end of a line. Not recommended.
Function and implementation
Use an ellipsis if material is omitted in the course of a quotation, unless square brackets are used to gloss the quotation (see above, and points below).
  • Put a space on each side of an ellipsis, except that there should be no space between an ellipsis and:
    • a quotation mark directly following the ellipsis
    • any (round, square, curly, etc.) bracket, where the ellipsis is on the inside
    • sentence-final punctuation, or a colon, semicolon, or comma (all rare), directly following the ellipsis
  • Sentence-final punctuation after an ellipsis is shown only if it is textually important (as is often the case with exclamation marks and question marks, and rarely with periods).
  • Use non-breaking spaces (&nbsp;) only as needed to prevent improper line breaks, for example:
    • To keep a quotation mark from being separated from the start of the quotation ("...&nbsp;we are still worried").
    • To keep the ellipsis from wrapping to the next line ("France, Germany,&nbsp;... and Belgium but not the USSR").
Pause or suspension of speech
Three periods (loosely also called ellipsis points) are occasionally used to represent a pause in or suspense of speech, in which case the punctuation is retained in its original form (Virginia's startled reply was: "Could he ...? No, I cannot believe it!"). Avoid this usage on Wikipedia, except in direct quotations.
With square brackets
An ellipsis does not normally need square brackets around it, because its function is usually obvious—especially if the guidelines above are followed. Square brackets, however, may optionally be used for precision, to make it clear that the ellipsis is not itself quoted; this is usually only necessary if the quoted passage also uses three periods in it to indicate a pause or suspension. The ellipsis should follow exactly the principles given above, but with square brackets inserted immediately before and after it (Her long rant continued: "How do I feel? How do you think I ... look, this has gone far enough! [...] I want to go home!").

Commas

Shortcut:
WP:COMMA

Commas are the most frequently used marks in punctuation. They can also be the most difficult to use well. Some important points are made in the Semicolons section below. Other points:

  • Pairs of commas are often used to delimit parenthetic material, forming a parenthetical remark. This interrupts the sentence less than a parenthetical remark in (round) brackets or dashes. Do not be fooled by other punctuation, which can mask the need for a comma, especially when it collides with a bracket or parenthesis, as in this example:
Incorrect: Burke and Wills, fed by local Aborigines (on beans, fish, and "ngardu") survived for a few months.
Correct:    Burke and Wills, fed by local Aborigines (on beans, fish, and "ngardu"), survived for a few months.
  • Modern practice is against excessive use of commas; there are usually ways to simplify a sentence so that fewer are needed.
Awkward: Mozart was, along with the Haydns, both Joseph and Michael, and also Beethoven, one of Schubert's heroes.
Much better:    Schubert's heroes included Mozart, Beethoven, and Joseph and Michael Haydn.

Serial commas

Shortcut:
MOS:SERIAL

A serial comma (also known as an Oxford comma or a Harvard comma) is a comma used immediately before a conjunction in a list of three or more items: the phrase ham, chips, and eggs includes a serial comma, while the variant ham, chips and eggs omits it. Editors may use either convention on Wikipedia so long as each article is consistent within itself. However, there are some times when the serial comma can create or remove confusion:

Sometimes omitting the comma can lead to an ambiguous sentence, as in this example: The author thanked her parents, Sinéad O'Connor and President Obama, which may list either four people (the two parents and the two people named) or two people (O'Connor and Obama, who are the parents).

Including the comma can also cause ambiguity, as in this example: The author thanked her mother, Sinéad O'Connor, and President Obama, which may list either two people (O'Connor, who is the mother, and Obama) or three people (the first being the mother, the second O'Connor, and the third Obama).

In such cases of ambiguity, there are three ways to clarify:

  • Use or omit the serial comma to avoid ambiguity.
  • Recast the sentence.
  • Format the list, such as with paragraph breaks and numbered paragraphs.

Recasting example one:

  • To list four people: The author thanked President Obama, Sinéad O'Connor, and her parents.
  • To list two people (the commas here set off non-restrictive appositives): The author thanked her father, President Obama, and her mother, Sinéad O'Connor.
    • Clearer (but more wordy): The author thanked her father and her mother, who are President Obama and Sinéad O'Connor respectively.

Recasting example two:

  • To list two people: The author thanked President Obama and her mother, Sinéad O'Connor.
  • To list three people: The author thanked her mother, President Obama, and Sinéad O'Connor.
    The clarity of the last example depends on the reader's knowing that Obama is male and cannot be a mother. If we change the example slightly, we are back to an ambiguous statement: The author thanked her mother, Irish President Mary McAleese, and Sinéad O'Connor.
    • Clearer: The author thanked President Obama, Sinéad O'Connor, and her mother; or The author thanked President Mary McAleese, Sinéad O'Connor, and her mother.

Colons

A colon (:) informs the reader that what comes after it demonstrates, explains, or modifies what has come before, or is a list of items that has just been introduced. The items in such a list may be separated by commas; or, if they are more complex and perhaps themselves contain commas, the items should be separated by semicolons:

We visited several tourist attractions: the Leaning Tower of Pisa, which I thought could fall at any moment; the Bridge of Sighs; the supposed birthplace of Petrarch, or at least the first known house in which he lived; and so many more.

A colon may also be used to introduce direct speech enclosed within quotation marks (see above).

In most cases a colon works best with a complete grammatical sentence before it. There are exceptions, such as when the colon introduces items set off in new lines like the very next colon here. Examples:

Correct: He attempted it in two years: 1941 and 1943.
Incorrect:    The years he attempted it included: 1941 and 1943.
Correct (special case):    Spanish, Portuguese, French: these, with a few others, are the West Romance languages.

Sometimes, more in American than British usage, the word following a colon is capitalized, if that word effectively begins a new grammatical sentence, and especially if the colon serves to introduce more than one sentence:

The argument is easily stated: We have been given only three tickets. There are four of us here: you, the twins, and me. The twins are inseparable. Therefore, you or I will have to stay home.

No sentence should contain more than one colon. There should never be a hyphen or a dash immediately following a colon.

Semicolons

A semicolon (;) is sometimes an alternative to a full stop (period), enabling related material to be kept in the same sentence; it marks a more decisive division in a sentence than a comma. If the semicolon separates clauses, normally each clause must be independent (meaning that it could stand on its own as a sentence); often, only a comma or only a semicolon will be correct in a given sentence.

Correct: Though he had been here before, I did not recognize him.
Incorrect:    Though he had been here before; I did not recognize him.

Above, "Though he had been here before" cannot stand on its own as a sentence, and therefore is not an independent clause.

Correct: Oranges are an acid fruit; bananas are classified as alkaline.
Incorrect:    Oranges are an acid fruit, bananas are classified as alkaline.

This incorrect use of a comma between two independent clauses is known as a comma splice; however, in very rare cases, a comma may be used where a semicolon would seem to be called for:

Accepted: "Life is short, art is long." (citing a brief aphorism; see Ars longa, vita brevis)
Accepted: "I have studied it, you have not." (reporting brisk conversation, like this reply of Newton's)

A semicolon does not force a capital letter in the word that follows it.

A sentence may contain several semicolons, especially when the clauses are parallel; multiple unrelated semicolons are often signs that the sentence should be divided into shorter sentences, or otherwise refashioned.

Unwieldy: Oranges are an acid fruit; bananas are classified as alkaline; pears are close to neutral; these distinctions are rarely discussed.
One better way:    Oranges are an acid fruit, bananas are alkaline, and pears are close to neutral; these distinctions are rarely discussed.

Hyphens

Shortcut:
WP:HYPHEN

Hyphens (-) indicate conjunction. There are three main uses.

  1. To distinguish between homographs (re-dress means dress again, but redress means remedy or set right).
  2. To link certain prefixes with their main word (non-linear, sub-section, super-achiever).
    • There is a clear trend to join both elements in all varieties of English (subsection, nonlinear), particularly in American English. British English tends to hyphenate when the letters brought into contact are the same (non-negotiable, sub-basement) or are vowels (pre-industrial), or where a word is uncommon (co-proposed, re-target) or may be misread (sub-era, not subera). American English reflects the same factors, but tends to close up without a hyphen when possible. Consult a good dictionary, and see WP:ENGVAR.
  3. To link related terms in compound adjectives and adverbs:
    • A hyphen can help with ease of reading (face-to-face discussion, hard-boiled egg); a hyphen is particularly useful in long nominal groups (noun phrases) where non-experts are part of the readership, such as in Wikipedia's scientific articles: gas-phase reaction dynamics.
    • A hyphen can help to disambiguate (little-celebrated paintings, not a reference to little paintings).
    • Many compound adjectives that are hyphenated when used attributively (before the noun they qualify: a light-blue handbag), are not hyphenated when used predicatively (after the noun: the handbag was light blue); this attributive hyphenation also occurs in proper names, such as Great Black-backed Gull. Where there would be a loss of clarity, the hyphen may be used in the predicative case too (hand-fed turkeys, the turkeys were hand-fed).
    • A hyphen is not used after a standard -ly adverb (a newly available home, a wholly owned subsidiary) unless part of a larger compound (a slowly-but-surely strategy). A few words ending in -ly function as both adjectives and adverbs (a kindly-looking teacher; a kindly provided facility). Some such dual-purpose words (like early, only, northerly) are not standard -ly adverbs, since they are not formed by addition of -ly to an independent current-English adjective. These need careful treatment: Early flowering plants evolved along with sexual reproduction, but Early-flowering plants risk damage from winter frosts; northerly-situated islands.
    • A hyphen is normally used when the adverb well precedes a participle used attributively (a well-meaning gesture; but normally a very well managed firm, since well itself is modified); and even predicatively, if well is necessary to, or alters, the sense of the adjective rather than simply intensifying it (the gesture was well-meaning, the child was well-behaved, but the floor was well polished).
    • In some cases, like diode–transistor logic, the independent status of the linked elements requires an en dash instead of a hyphen. See En dashes below.
    • A hanging hyphen is used when two compound adjectives are separated (two- and three-digit numbers, a ten-car or -truck convoy, sloping right- or leftward, but better is sloping rightward or leftward).
    • Values and units used as compound adjectives are hyphenated only where the unit is given as a whole word. Where hyphens are not used, values and units are always separated by a non-breaking space (&nbsp;).
Incorrect: 9-mm gap
Correct: 9 mm gap (entered as 9&nbsp;mm gap)
Incorrect:    9 millimetre gap
Correct: 9-millimetre gap
Correct: 12-hour shift
Correct: 12 h shift

Multi-hyphenated items: It is often possible to avoid multi-word hyphenated adjectives by rewording (a four-CD soundtrack album may be easier to read as a soundtrack album of four CDs). This is particularly important where converted units are involved (the 6-hectare-limit (14.8-acre-limit) rule might be possible as the rule imposing a limit of 6 hectares (14.8 acres), and the ungainly 4.9-mile (7.9 km) -long tributary as simply 4.9-mile (7.9 km) tributary).

Spacing: A hyphen is never followed or preceded by a space, except when hanging (see above) or when used to display parts of words independently, such as the prefix sub- and the suffix -less.

Minus signs: Do not use a hyphen (-) as a minus sign (), except in code (see below); the correct character for general use is U+2212 MINUS SIGN.

Image filenames and redirects: A hyphen is used only to mark conjunction, not disjunction (for which en dashes are used: see below). An exception is in image filenames, where the ability to type the URL becomes more important (see the section on dashes below). Article titles with dashes should have a corresponding redirect from the title with hyphens: for example, Michelson-Morley experiment redirects to Michelson–Morley experiment, as the latter title, while correct, is harder to search for.

Hyphenation involves many subtleties that cannot be covered here; the rules and examples presented above illustrate the broad principles that inform current usage.

Dashes

Shortcuts:
MOS:DASH
WP:DASH

Two kinds of dashes are used on Wikipedia: en dashes and em dashes. The article on dashes shows common input methods for these.

Dashes should never be used in the filenames of images (use hyphens instead). Where used in an article's title, there should be a redirect from the version with a hyphen.

En dashes

En dashes () have three distinct roles.

  1. To indicate disjunction. There are three uses.
    • To stand for to or through in ranges (pp. 211–19, 64–75%, the 1939–45 war). Ranges expressed using prepositions (from 450 to 500 people or between 450 and 500 people) should not use dashes (not from 450–500 people or between 450–500 people). Number ranges must be spelled out if they involve a negative value or might be misconstrued as a subtraction (−10 to 10, not −10–10).
    • To stand for to or versus (male–female ratio, 4–3 win, Lincoln–Douglas debate, France–Germany border).
    • To stand for and between independent elements (diode–transistor logic, Michelson–Morley experiment). An en dash is not used for a hyphenated name (Lennard-Jones potential, named after John Lennard-Jones) or an element that lacks lexical independence (the prefix Sino- in Sino-Japanese trade).
  2. In lists, to separate distinct information within points—for example, in articles about music albums, en dashes are used between track titles and durations, and between musicians and their instruments. In this role, en dashes are always spaced.
  3. As a stylistic alternative to em dashes (see below).
Spacing

Disjunctive en dashes are unspaced, except when there is a space within either one or both of the items (the New York – Sydney flight; the New Zealand – South Africa grand final; June 3, 1888 – August 18, 1940, but June–August 1940). Exceptions are occasionally made where the item involves a spaced surname (Seifert–van Kampen theorem).

En dashes in page names

When naming an article, a hyphen is not used as a substitute for an en dash that properly belongs in the title, for example in Eye–hand span. However, editors should provide a redirect page to such an article, using a hyphen in place of the en dash (Eye-hand span), to allow the name to be typed easily when searching Wikipedia. See also Wikipedia:Naming conventions (precision). The names of a page and its associated talk page should match exactly.

Minus signs

Do not use an en dash for negative signs and subtraction operators: use the correct Unicode character for the minus sign (U+2212 MINUS SIGN, HTML &minus;); see also Wikipedia:Manual of Style (mathematics). Negative signs (−8 °C) are unspaced; subtraction operators (42 − 4 = 38) are spaced.

Em dashes

Shortcuts:
MOS:EMDASH
WP:EMDASH

Em dashes () indicate interruption in a sentence. They are used in two roles.

  1. Parenthetical (Wikipedia—one of the most popular web sites—has the information you need). A pair of em dashes for such interpolations is more arresting than a pair of commas, and less disruptive than round brackets.
  2. As a sharp break in the flow of a sentence—sharper than is provided by a colon or a semicolon.
  • In both roles, em dashes are useful where there are already several commas; em dashes can clarify the structure, sometimes removing ambiguity.
  • Use em dashes sparingly. They are visually striking, so two in a paragraph is often a good limit. Ensure there is no ambiguity if using multiple "sharp break" or parenthetical em dashes in the same area of the text.
  • Em dashes should not be spaced.
  • Do not use an em dash for a minus sign.
Spaced en dashes as an alternative to em dashes
Spaced en dashes – such as here – can be used instead of unspaced em dashes in all of the ways discussed above. Spaced en dashes are used by several major publishers, to the complete exclusion of em dashes. One style should be used consistently in an article.

Other dashes

Do not use substitutes for em or en dashes, such as the combination of two hyphens (--).

Slashes

Shortcuts:
WP:SLASH
MOS:SLASH

Generally avoid joining two words by a slash, also known as a forward slash or solidus ( / ). It suggests that the two are related, but does not specify how. It is often also unclear how the construct would be read aloud. Replace with clearer wording.

An example: The parent/instructor must be present at all times. Must both be present? (Then write the parent and the instructor.) Must at least one be present? (Then write the parent or the instructor.) Are they the same person? (Use a hyphen: the parent-instructor.)

In circumstances involving a distinction or disjunction, the en dash (see above) is usually preferable to the slash: the digital–analog distinction.

An unspaced slash may be used:

  • to indicate phonemic pronunciations (ribald is pronounced /ˈrɪbəld/)
  • to separate the numerator and denominator in a fraction (7/8 or 78)
  • to indicate regular defined yearly periods that do not coincide with calendar years (see Wikipedia:Manual of Style (dates and numbers)#Longer periods)
  • where a slash occurs in a phrase widely used outside Wikipedia, and a different construction would be inaccurate, unfamiliar, or ambiguous

A spaced slash may be used:

  • to separate run-in lines when quoting poetry or song (To be or not to be: that is the question: / Whether 'tis nobler in the mind to suffer / The slings and arrows of outrageous fortune), or rarely when quoting prose, where careful marking of a paragraph break is textually important
  • to separate items that include at least one internal space (the NY 31 east / NY 370 exit), where for some reason use of a slash is unavoidable

Spaced slashes should be coded with a leading non-breaking space and a trailing normal space, as in x&nbsp;/ y (which renders as x / y), to prevent improper line breaks.

Do not use the backslash character ( \ ) in place of a slash.

Prefer the division operator ( ÷ ) to ( / ) when representing elementary arithmetic in general prose: 10 ÷ 2 = 5. In more advanced mathematical formulas, a vinculum or slash is preferred: \textstyle\frac{x^n}{n!} or xn/n!. (See Wikipedia:Manual of Style (dates and numbers)#Common mathematical symbols and Help:Displaying a formula.)

And/or

Shortcut:
MOS:ANDOR

The construct and/or is awkward. In general, where it is important to mark an inclusive or, use x or y, or both, rather than x and/or y. For an exclusive or, use either x or y, and optionally add but not both, if it is necessary to stress the exclusivity.

Where more than two possibilities are presented, from which a combination is to be selected, it is even less desirable to use and/or. With two possibilities, at least the intention is clear; but with more than two it may not be. Instead of x, y, and/or z, use an appropriate alternative, such as one or more of x, y, and z; some or all of x, y, and z.

Sometimes or is ambiguous in another way: Wild dogs, or dingoes, inhabit this stretch of land. Are wild dogs and dingoes the same or different? For one case write: wild dogs (dingoes) inhabit ... (meaning dingoes are wild dogs); for the other case write: either wild dogs or dingoes inhabit ....

Number signs

Shortcuts:
MOS:NUMBERSIGN
MOS:HASH
MOS:POUND
MOS:NUMERO
  • Avoid using the # symbol (known as the number sign, hash sign, or pound sign) when referring to numbers or rankings. Instead use the word "number", or the abbreviation "No." For example:
Incorrect:    Her album reached #1 in the UK album charts.
Correct: Her album reached No. 1 in the UK album charts.
  • Similarly, the symbol should also be avoided.

Punctuation at the end of a sentence

Shortcuts:
MOS:FULLSTOP
MOS:EXCLAMATION
  • Periods (also called "full stops"), question marks, and exclamation marks are the three sentence-enders, the only punctuation marks used to end sentences.
  • In some contexts, no sentence-ender should be used. In such cases, the sentence often does not start with a capital letter. See Quotations, Quotation marks, and Sentences and brackets, above.
  • For the use of three periods in succession, see Ellipses, above.
  • Clusters of question marks, exclamation marks, or a combination of them (such as the interrobang) are highly informal, and inappropriate in Wikipedia articles.
  • The exclamation mark is used with restraint. It is an expression of surprise or emotion that is generally unsuited to a scholarly or encyclopedic register.
  • Question marks and exclamation marks may sometimes be used in the middle of a sentence:
    • Why me? she wondered.
    • The Homeric question is not Did Homer write the Iliad? but How did the Iliad come into being?, as we have now come to realize.
    • The door flew open with a BANG! that made them jump. [Not encyclopedic, but acceptable in transcription from audio, or of course in direct quotation.]
  • In normal prose, never place a space before commas, semicolons, colons, or sentence-enders.
  • The number of spaces following the end of a sentence makes no difference on Wikipedia because web browsers condense any number of spaces to just one. (See Double spacing at the end of sentences#Web browsers.) However, editors may use any spacing style they are comfortable with in Wikipedia. Multiple spacing styles may coexist in the same article, and adding or removing a double space is sometimes used as a dummy edit.

Punctuation and inline citations

Shortcuts:
WP:PAIC
MOS:PAIC

Place inline citations after any punctuation, such as a comma or period, with no intervening space:

The Sun's diameter is about 800,000 kilometres,<ref>Miller, E: ' 'The Sun' ', page 23. Academic Press, 2005.</ref> which dwarfs that of the Moon.<ref>Brown, R: "Size of the Moon", ' 'Scientific American' ', 51(78):46</ref>

This will yield:

The Sun is pretty big,[1] but the Moon is not so big.[2]

and in the Notes section below:

  1. ^ Miller, E: The Sun, page 23. Academic Press, 2005.
  2. ^ Brown, R: "Size of the Moon", Scientific American, 51(78):46.

See Wikipedia:Citing sources for more about citations.

Punctuation after formulae

A sentence that ends with a formula should have a sentence-ender (period, exclamation mark, or question mark) after the formula. Within a sentence, other punctuation (such as comma or colon) is used after a formula just as it would be if the text were not a formula. See Wikipedia:Manual of Style (mathematics)#Punctuation after formulae.

Geographical items

Places should generally be referred to consistently using the same name as in the title of their article (see Wikipedia:Naming conventions (geographic names)). Exceptions are made if there is a widely accepted historical English name appropriate to the given context. In cases where such a historical name is used, it should be followed by the modern name in round brackets on the first occurrence of the name in applicable sections of the article. This resembles linking; it should not be done to the detriment of style. On the other hand, it is probably better to provide such a variant too often than too rarely. If more than one historical name is applicable for a given context, the other names should be added after the modern English name, that is: "historical name (modern name, other historical names)".

Chronological items

Precise language

Avoid statements that will age quickly, except on pages concerning current events which are frequently brought up to date. Avoid recently, soon, and now (unless their meaning is fixed by the context). Avoid relative terms like currently (usually redundant), in modern times, is now considered, and is soon to be superseded. Instead, use either:

  • more precise and absolute expressions (since the start of 2005; during the 1990s; is expected to be superseded by 2008); or
  • an as of phrase (as of August 2007), which signals the time-dependence of the statement, and alerts later editors to update the statement (see As of); or simply use at instead: The population was over 21,000,000 (at December 2008).

Times

Context determines whether the 12-hour clock or 24-hour clock is used; in both, colons separate hours, minutes, and seconds (1:38:09 pm and 13:38:09).

  • 12-hour clock times should end with dotted or undotted lower-case a.m. or p.m., or am or pm, which are spaced (2:30 p.m. or 2:30 pm, not 2:30p.m. or 2:30pm). A hard space (see above) is advisable: 2:30&nbsp;pm. Use noon and midnight rather than 12 pm and 12 am; whether midnight refers to the start or the end of a date will need to be specified unless this is clear from the context.
  • 24-hour clock times have no a.m., p.m., noon, or midnight suffix. Use discretion as to whether the hour has a leading zero (08:15 or 8:15). 00:00 refers to midnight at the start of a date, 12:00 to noon, and 24:00 to midnight at the end of a date.

Dates

  • Wikipedia does not add ordinal suffixes (such as -nd) or the, or put a comma between month and year.
Incorrect:    February 14th, 14th February, the 14th of February
Correct: 14 February, February 14
Incorrect: October, 1976; October of 1976
Correct: October 1976
  • For guidance on which of the two standard formats to use (day before month or month before day), see Wikipedia:Manual of Style (dates and numbers)#Full date formatting.
  • Dates are not normally linked.[4]
  • Date ranges are preferably given with minimal repetition, using an unspaced en dash where the range involves numerals alone (5–7 January 1979; January 5–7, 2002) or a spaced en dash where the opening or the closing date has internal spaces (5 January – 18 February 1979; January 5 – February 18, 1979).
  • Rarely, a night may be expressed in terms of the two contiguous dates using a slash (the bombing raids of the night of 30/31 May 1942).
  • Yearless dates (5 March, March 5) are inappropriate unless the year is obvious from the context. There is no such ambiguity with recurring dates, such as January 1 is New Year's Day.
  • Dates in the format YYYY-MM-DD (like 1976-05-13) are uncommon in English prose and are generally not used in article prose. However, they may be useful in long lists, references, and tables for conciseness and ease of comparison.

Longer periods

  • Write months as whole words (February, not 2), except in the YYYY-MM-DD format (as in 2000-04-01). Use abbreviations such as Feb only where space is extremely limited, such as in tables and infoboxes. Do not insert of between a month and a year (April 2000, not April of 2000).
  • Seasons as dates. As the seasons are reversed in the northern and southern hemispheres—and areas near the equator tend to have just wet and dry seasons—neutral wording (in early 1990, in the second quarter of 2003, around September) is usually preferable to a "seasonal" reference (summer 1918, spring 1995). Even when the season reference is unambiguous (for instance when a particular location is clearly involved) a date or month may be preferable to a season name, unless there is a logical connection (the autumn harvest). Season names are preferable, however, when they refer to a phase of the natural yearly cycle (migration to higher latitudes typically starts in mid-spring).
  • Season names are not normally capitalized; for exceptions see Calendar items, above.
  • Years
    • Years are normally expressed in digits; a comma is not used in four-digit years (1988, not 1,988).
    • Avoid inserting the words the year before the digits (1995, not the year 1995), unless the meaning would otherwise be unclear.
    • Years are numbered according to the western calendar eras based on the traditionally reckoned year of the conception or birth of Jesus.
      • AD and BC are the traditional ways of referring to these eras. However, CE and BCE are becoming more common in academic and some religious writing. No preference is given to either style.
        • Do not use CE or AD unless the date would be ambiguous without it (The Norman Conquest took place in 1066; not 1066 CE or AD 1066).
        • BCE and CE or BC and AD are written in upper case, spaced, and without periods (full stops).
        • Use either the BC–AD or the BCE–CE notation, but not both in the same article. AD may appear before or after a year (AD 106, 106 AD); the other abbreviations appear after (106 CE, 3700 BCE, 3700 BC).
      • Uncalibrated (bce) radiocarbon dates: Do not give uncalibrated radiocarbon dates (represented by the lower-case bce unit, occasionally bc or b.c. in some sources), except in directly quoted material, and even then include a footnote, a square-bracketed editor's note (such as ... 1360 bce [uncalibrated]), or other indication to the reader what the calibrated date is, or at least that the date is uncalibrated. Calibrated and uncalibrated dates can diverge surprisingly widely, and the average reader does not recognize the distinction between bce and BCEBC.
      • Year ranges, like all ranges, are separated by an en dash: do not use a hyphen or slash (2005–06 for a 24-month period, not 2005-06 or 2005/06. A closing CE–AD year is normally written with two digits (1881–86) unless it is in a different century from that of the opening year (1881–1986). The full closing year is acceptable, but abbreviating it to a single digit (1881–6) or three digits (1881–886) is not. A closing BCE–BC year is given in full (2590–2550 BCE). While one era signifier at the end of a date range still requires an unspaced en dash (12–5 BC), a spaced en dash is required when a signifier is used after the opening and closing years (5 BC – 29 AD).
      • A slash may be used to indicate regular defined yearly periods that do not coincide with calendar years (the financial year 1993/94).
      • Abbreviations indicating long periods of time ago—such as BP (Before Present), as well as various annum-based units such as ka (kiloannum) and kya (thousand years ago), Ma (megaannum), and Mya (million years ago), and Ga (gigaannum or billion years ago)—are given as full words and wikilinked on first occurrence.
      • To indicate around, approximately, or about, the abbreviations c. and ca. are preferred over circa, approximately, or approx., and are spaced (c. 1291). Use a question mark instead (1291?) only if the date is in fact questioned rather than approximate. (The question mark may mistakenly be understood as a sign that editors have simply not checked the date.)
  • Decades contain no apostrophe (the 1980s, not the 1980's); the two-digit form is used only where the century is clear (the '80s or the 80s).
  • Centuries and millennia are written using ordinal numbers, without superscripts and without Roman numerals: the second millennium, the 19th century, a 19th-century book (see also Numbers as figures or words below).

Numbers

Numbers as figures or words

  • Generally, for both ordinal numbers and cardinal numbers in the running text of an article:
    • Render single-digit whole numbers from zero to nine as words.
    • Render numbers greater than nine as figures or, with consistency within each article, render numbers over nine that take two words or fewer to say as words (about five million people; 16 or sixteen; 84 or eighty-four; 200 or two hundred; but 3.75, 544, 21 million). Words may be preferable for approximations.
  • Use figures in tables and infoboxes and in places where space is limited. Numbers within a table's explanatory text and comments should be consistent with the general rule above.
  • Show precise mathematical quantities, measurements, stock prices, etc., as figures.
  • Render comparable quantities, mentioned together, either all as words or all as figures (5 cats and 32 dogs, or five cats and thirty-two dogs; but not five cats and 32 dogs).
  • Render differently (with words or figures) adjacent quantities that are not comparable (thirty-six 6.4-inch rifled guns; not 36 6.4-inch rifled guns).
  • Render as words numbers that begin sentences. However, it is often better to recast the sentence so that it does not start with a number.
  • Do not use words for the numerical elements of dates and times, except where words are customary (Seventh of March Speech).
  • Show centuries in figures (the 5th century CE; 19th-century painting).
  • Use words for simple fractions; but use the numerical fraction form in a percentage, with an abbreviated unit, or mixed with whole numbers (an eighth of a millimetre, but 18 mm; 1+14 slices). Use figures for decimal fractions (0.025).
  • Write proper names, idioms, and formal numerical designations in compliance with common usage, case by case (Chanel No. 5, 4 Main Street, 1-Naphthylamine, Channel 6). Do this even where it would cause a figure to open a sentence, although this can usually be avoided by rewording. Most proper names that include numbers use words (Fourth Amendment; Seventeenth Judicial District; Seven Years' War); but the proper names of military units do not.

Large numbers

  • Use commas to break the sequence every three places: 2,900,000.
  • Because large rounded numbers are generally assumed to be approximations, about or similar qualifications are not normally needed.
  • Avoid over-precise values where they are unlikely to be stable or accurate, or where the precision is unnecessary in the context (The speed of light in a vacuum is 299,792,458 metres per second; but perhaps not The distance from the Earth to the Sun is 149,014,769 kilometres, since that distance varies; and not The population of Cape Town is 2,968,790, also variable, and unlikely to be accurate or useful).
  • In scientific contexts scientific notation is preferred (6.02 × 1023).
  • Where values in the millions occur a number of times through an article, upper-case M may be used for million, unspaced, and after using the full word at the first occurrence (She bequeathed her fortune of £100 million unequally: her daughter received £70M, her husband £18M, and her three sons just £4M each).
  • Billion is understood as 109. After the first occurrence in an article, billion may be abbreviated to unspaced bn ($35bn).

Decimal points

  • Use a decimal point between the integral and the fractional parts of a decimal number, not a comma or a raised dot (6.57, not 6,57 or 6·57).
  • The number of decimal places should be consistent with others in the same context (The response rates were 41.0 and 47.4 percent, respectively; not The response rates were 41 and 47.4 percent, respectively), except for some rare cases in which the measurements were taken with unequal precision.
  • Use a leading zero for numbers between negative one and positive one (0.02, not .02), except in certain customary usages, such as sports performance averages and terms such as .22 caliber.

Percentages

  • Generally, use either percent or per cent to indicate percentages in the body of an article.
  • The percentage symbol (%) is preferred in scientific or technical articles, in complex listings, and in articles where many percentages are reported.
  • Do not put a space before the symbol (71%, not 71 %).
  • In tables and infoboxes, use the percentage symbol, not the words (71%, not percent or per cent).
  • For ranges, use one percentage symbol, not two (22–28%, not 22%–28%).

Currencies

  • In non-country-specific articles, express amounts of money in United States dollars; you may also add conversions to euros, pounds sterling, or both.
  • In country-specific articles, use the currency of the country, together with approximate conversions to U.S. dollars, euros, pounds, or a combination of these: for example, Since 2001 the grant has been 10,000,000 Swedish kronor (approx. US$1.4M, €1.0M, or £800k as of August 2009).
  • Generally, use the full name of a currency on its first appearance (52 Australian dollars); subsequent occurrences can use the currency sign (just $88).
  • Most currency signs are placed before the number; they are unspaced ($123), except for alphabetic signs (R 75).

Units of measurement

The use of units of measurement is guided by the following principles:

  • Avoid ambiguity: Aim to write so you cannot be misunderstood.
  • Familiarity: The less readers have to look up definitions, the easier it is to be understood.
  • International scope: Wikipedia is not country-specific; apart from some regional or historical topics, use the units in most widespread use worldwide for the type of measurement in question.

In instances where these principles appear to conflict with one another, consult other editors on the article's talk page and try to reach consensus.

Which units to use and how to present them

When different parts of the English-speaking world use different units for the same measurement, the "primary" unit should be followed by a conversion in round brackets. This will enable readers from all over the world to understand the measurement: for example, the Mississippi River is 2,320 miles (3,734 km) long; the Murray River is 2,375 kilometres (1,476 mi) long. (See Unit conversions below.)

Apply the following guidelines when choosing the "primary" unit for a measurement:

  • With topics strongly associated with places, times or people, put the units most appropriate to them first. For example, in US articles, they usually are United States customary units, and for the UK, they usually are metric units for most measurements, but imperial units for some measurements such as road distances and personal heights and weights (see, for example, Metrication in the United Kingdom and the the Times Online style guide under "Metric").
  • If editors cannot agree on the sequence of units, put the source value first and the converted value second. If the choice of units is arbitrary, use SI units as the main unit, with converted units in round brackets.
  • Avoid inconsistent usage. Write a 600 metre (2000 ft) hill with a 650 metre (2,100 ft) hill, not a 2,000 foot (610 m) hill with a 650 metre (2,100 ft) hill.
  • Nominal and defined values should be given in the original units first, even if this makes the article inconsistent: for example, When the Republic of Ireland adopted the metric system, the road speed limit in built-up areas was changed from 30 miles per hour (48 km/h) to 50 kilometres per hour (31 mph). (The focus is on the change of units, not on the 3.6% increase.)
  • Avoid ambiguous unit names (imperial gallon or US gallon rather than just gallon). Only in the rarest of instances should ambiguous units be used, such as in direct quotations, to preserve the accuracy of the quotation.
  • In scientific articles, use the units employed in the current scientific literature on that topic. This will usually be SI, but not always; for example, natural units are often used in relativistic and quantum physics, and Hubble's constant should be quoted in its most common unit of (km/s)/Mpc rather than its SI unit of s−1.
  • Some disciplines use units not approved by the BIPM, or write them differently from BIPM-prescribed format. When a clear majority of the sources relevant to those disciplines use such units, articles should follow this (using cc in automotive articles for example; and not cm3). Such non-standard units are always linked on first use.
  • Use familiar units rather than obscure units; do not write over the heads of the readership (for example, a general-interest topic such as black holes would be best served by having mass expressed in solar masses, but it might be appropriate to use Planck units in an article on the mathematics of black hole evaporation).

Unit conversions

Shortcut:
MOS:CONVERSIONS
  • Generally, conversions to and from metric units and US or imperial units should be provided, except:
    • articles on scientific topics where there is consensus among the contributors not to convert the metric units, in which case the first occurrence of each unit should be linked;
    • where units are part of the topic, such as knots in naval articles, and only the first use of a unit needs conversion and linking;
    • where inserting a conversion would make a common expression awkward (The four-minute mile).
  • In the main text, give the main units as words and use unit symbols or abbreviations for conversions in round brackets; for example, a pipe 100 millimetres (4 in) in diameter and 16 kilometres (10 mi) long or a pipe 4 inches (100 mm) in diameter and 10 miles (16 km) long. However, where there is consensus to do so, the main units may also be abbreviated in the main text after the first occurrence.
  • Converted values should use a level of precision similar to that of the source value, so the Moon is 380,000 kilometres (240,000 mi) from Earth, not (236,121 mi). However, small numbers may need to be converted to a greater level of precision where rounding would cause a significant distortion, so one mile (1.6 km), not one mile (2 km).
  • Category:Conversion templates can be used to convert and format many common units, including {{convert}}, which includes non-breaking spaces.
  • In a direct quotation:
    • conversions required for units cited within direct quotations should appear within square brackets in the quote;
    • if the text contains an obscure use of units (five million board feet of lumber), annotate it with a footnote that provides standard modern units, rather than changing the text of the quotation.
  • Measurements should be accompanied by a proper citation of the source using a method described at the style guide for citation.
  • Where footnoting or citing sources for values and units, identify both the source and the original units.

Clarify ambiguous units

Unnecessary vagueness

Use accurate measurements whenever possible.

Vague Precise
The wallaby is small. The average male wallaby is 1.6 metres (63 in) from head to tail.
Prochlorococcus marinus is a tiny cyanobacterium. The cyanobacterium Prochlorococcus marinus is 0.5 to 0.8 micrometres across.
The large oil spill stretched a long way down the Alaskan coast. The oil spill that drifted down the Alaskan coast was 3 statute miles (5 km) long and 1,000 feet (300 m) wide.

Unit symbols and abbreviations

  • Non-breaking spaces are used between values and unit symbols; see the Non-breaking spaces section above. (When values and spelled out units form a compound adjective, they are separated by a hyphen; see the Hyphens section above.)
  • Standard abbreviations and symbols for units are undotted (do not carry periods). Examples: m for metre (meter) and kg for kilogram (not m. or kg.); in for inch (not in.,  or ); ft for foot (not ft.; or ); and lb for pound (not lb. or #).
  • The degree symbol is °. Using any other symbol (such as masculine ordinal º or "ring above" ˚) for this purpose is incorrect.
  • Do not append an -s for the plurals of unit symbols (kg, km, in, lb, not kgs, kms, ins, lbs). A lowercase s is the SI symbol for second; thus, kgs can be confused with kg s, which means "kilogram-second".
  • Temperatures are always accompanied by °C for degrees Celsius, °F for degrees Fahrenheit, or K (but not °K) for kelvin. Further, a space—preferably a non-breaking space (&nbsp;)—always separates the value and temperature symbol (35 °C; 62 °F; 5,000 K).
  • In most cases, a space—preferably a non-breaking space (&nbsp;)—separates numeric values and unit symbols (25 kg, not 25kg). The exceptions are the percent symbol (%) and the symbols for degrees, minutes and seconds of plane angle (a 25% share; the coordinate is 5° 24′ 21.12″ N; the pathways meet at a 90° angle).
  • Squared and cubic metric-symbols are always expressed with a superscript exponent (5 km2, 2 cm3); squared imperial and US unit abbreviations may be rendered with sq, and cubic with cu (15 sq mi, 3 cu ft).
  • Do not use the Unicode characters ² and ³, but rather write <sup>2</sup> and <sup>3</sup> to produce the superscripts 2 and 3. The superscripted 2 and 3 are easier to read, especially on small displays, and ensure that exponents are properly aligned (compare wmx²y³zn to wmx2y3zn).
  • In tables and infoboxes, use symbols and abbreviations for units, not words.
  • Ranges are preferably formatted with one rather than two unit signifiers (5.9–6.3 kg, not 5.9 kg – 6.3 kg).

Common mathematical symbols

  • For a negative sign or subtraction operator, use a minus sign (), input by clicking on it in the insert box beneath the edit window or by typing &minus;.
  • For a multiplication sign between numbers, use ×, which is input by clicking on it in the edit toolbox under the edit window or by typing &times;. However, the unspaced letter x is accepted as a substitute for by in such terms as 4x4.
  • Exponentiation is indicated using a superscript, an (typed as a<sup>n</sup>). Exponential notation can be spaced or unspaced, depending on circumstances.
    • In many programming languages, the subtraction, multiplication and exponentiation are respectively represented by the hyphen-minus -, the asterisk *, and the caret or double asterisk ^ or **, and exponential notation is denoted by E notation. Do not use these unless writing code.
  • Symbols for binary operators and relations are spaced on both sides:
    • plus, minus, and plus-or-minus (as binary operators): +, , ± (as in 5 − 3);
    • multiplication and division: ×, ÷;
    • equals, does not equal, equals approximately: =, , ;
    • is less than, is less than or equal to, is greater than, is greater than or equal to: <, , >, .
  • Symbols for unary operators are closed-up to their operand:
    • positive, negative, and positive-or-negative signs: +, , ± (as in −3);
    • other unary operators, such as the exclamation mark as a factorial sign (as in 5!).

Simple tabulation

Lines that start with blank spaces in the editing window are displayed boxed and in a fixed-width font, for simple tabulation. Lines that contain only a blank space insert a blank line into the table. For a complete guide to constructing tables, see Meta:Help:Table.

Grammar

Possessives

For thorough treatment of the English possessive see Apostrophe. See also Apostrophes, above.

For a template which can be used to avoid confict with the use of apostrophes in Wiki markup see Template:'. Alternatives to the use of the template include using <nowiki>'</nowiki> or the code &#39;

Nouns
  • For the possessive of most singular nouns, add 's (my daughter's achievement, my niece's wedding, Cortez's men, the boss's wife, Glass's books, Illinois's largest employer, Descartes's philosophy, Verreaux's eagle). Exception: abstract nouns ending with an /s/ sound, when followed by sake (for goodness' sake, for his conscience' sake).
  • For the possessive of singular nouns ending with just one s (sounded as /s/ or /z/), there are three practices:
    1. Add 's: James's house, Sam Hodges's son, Jan Hus's life, Vilnius's location, Brahms's music, Dickens's novels, Morris's works, the bus's old route.
    2. Add just an apostrophe: James' house, Sam Hodges' son, Jan Hus' life, Vilnius' location, Brahms' music, Dickens' novels, Morris' works, the bus' old route.
    3. Add either 's or just an apostrophe, according to how the possessive is pronounced:
      • Add only an apostrophe if the possessive is pronounced the same way as the non-possessive name: Sam Hodges' son, Moses' leadership;
      • Add 's if the possessive has an additional /ɪz/ at the end: Jan Hus's life, Morris's works.
      • Some possessives have two possible pronunciations: James's house or James' house, Brahms's music or Brahms' music, Vilnius's location or Vilnius' location, Dickens's novels or Dickens' novels.
  • Whichever of the above three options is chosen, it must be applied consistently within an article. When using the third option, if there is disagreement over the pronunciation of a possessive, the choice should be discussed and then that possessive adopted consistently in an article. (Possessives of certain classical and biblical names may have traditional pronunciations which may be deemed as taking precedence: Jesus' answer and Xerxes' expeditions, but Zeus's anger; and in some cases—particularly possessives of inanimate objects—rewording may be an option: the location of Vilnius, the old bus route, the moons of Mars.)
  • For a normal plural noun, ending with a pronounced s, form the possessive by adding just an apostrophe (my sons' wives, my nieces' weddings).
  • For a plural noun not ending with a pronounced s, add 's (women's careers, people's habits; The two Dumas's careers were controversial, but where rewording is an option, this may be better: The career of each Dumas was controversial).
  • Official names (of companies, organizations, or places) should not be altered (St Thomas' Hospital should therefore not be rendered as St Thomas's Hospital, even for consistency).
Pronouns
  • The possessive its (the dog chased its tail) has no apostrophe. (It's is the short form of it is or it has: it's a nice day, it's been a nice day.) Hers, ours, yours, theirs, and whose likewise lack apostrophes. Possessives of non-personal pronouns such as everyone, nobody, and anyone else are formed as if they were nouns (everyone's mother, nobody's hat, anyone else's opinion).

First-person pronouns

Wikipedia articles must not be based on one person's opinions or experiences, so the pronoun I is never used, except when it appears in a quotation. For similar reasons, avoid the pronoun we; a sentence such as We should note that some critics have argued in favor of the proposal sounds more personal than encyclopedic.

It is however acceptable to use we in figures of speech in which it is not meant as a literal reference to the author's personal viewpoint. For example:

  • In historical articles to mean the modern world as a whole: The text of De re publica has come down to us with substantial sections missing.
  • The author's we found in scientific writing. Albert Einstein wrote: "We are thus led also to a definition of "time" in physics." When one writes "Throughout the proof of this theorem we assume that the function ƒ is uniformly continuous.", it means that the proof is valid in cases in which that assumption is true.

Second-person pronouns

Shortcut:
WP:YOU

Use of the second person you, which is often ambiguous and contrary to the tone of an encyclopedia, is discouraged. Instead, refer to the subject of the sentence or use the passive voice, for example:

Do not use: When you move past "Go", you collect $200.
Use: When a player moves past "Go", that player collects $200.
Use: Players passing "Go" collect $200.
Use: $200 is collected when passing "Go".

Gender-neutral language[R]

Use gender-neutral language where this can be done with clarity and precision. This does not apply to direct quotations or the titles of works (The Ascent of Man), which are of course not to be altered; nor where all referents are of one gender, such as in an all-female school (When any student breaks that rule, she loses privileges).

Contested vocabulary

Avoid words and phrases that give the impression of straining for formality, that are unnecessarily regional, or that are not widely accepted. See List of English words with disputed usage, Words to avoid, and List of commonly misused English words; see also Identity and Gender-neutral language below.

Contractions

Shortcut:
WP:CONTRACTION

In general, the use of contractions—such as don't, can't, won't, they'd, should've, it's—is informal and should be avoided.

Instructional and presumptuous language

Shortcut:
MOS:NOTED

Avoid such phrases as remember that and note that, which address readers directly in an unencyclopedic tone. Similarly, phrases such as of course, naturally, obviously, clearly, and actually can make presumptions about readers' knowledge, and call into question the reason for including the information in the first place. See Wikipedia:Words to avoid.

We do not need to tell our readers that something is ironic, surprising, unexpected, amusing, coincidental, etc. Doing so inappropriately presents an editorial point of view. Simply state the sourced facts and allow readers to draw their own conclusions. The resulting prose is often considerably more powerful.

Subset terms

A subset term identifies a set of members of a larger class. Common subset terms are including, among, and et cetera (etc.). Do not use two subset terms (so avoid constructions like these: Among the most well-known members of the fraternity include ...; The elements in stars include hydrogen, helium and iron, etc.). Do not use including to introduce a complete list, where comprising, consisting of, or composed of would be correct.

Plurals

Shortcut:
WP:PLURALS

Use the appropriate plural; allow for cases (such as oblast or octopus) in which a foreign word has been assimilated into English and normally takes an s or es plural, not its original plural.

Many words, like army, company, crowd, fleet, government, majority, mess, number, pack, and party may refer either to a single entity or to the members that compose it. In British English, such words are commonly treated as singular or plural according to context. Names of towns and countries take plural verbs when they refer to sports teams but singular verbs when they refer to the actual place (or to the club as a business enterprise): in England are playing Germany tonight, the word England refers to a football team, but in England is the most populous country of the United Kingdom, it refers to the country. In North American English, these words (and the United States, for historical reasons) are almost invariably treated as singular. See WP:ENGVAR.

Ampersand

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The ampersand (&) represents the word and. In running prose, and should be used instead. Retain ampersands in titles of works or organizations. Ampersands may be used with consistency and discretion in tables, infoboxes, and similar contexts where space is limited. Modern editions of old texts routinely replace ampersands with and (just as they replace other disused glyphs and ligatures), so an article's quotations may be cautiously modified, especially for consistency in quotations where different editions are used. (For similar allowable modifications see Quotations, above.)

National varieties of English

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WP:ENGVAR
WP:AmE
WP:BrE

The English Wikipedia does not prefer any major national variety of the language. Within the English Wikipedia no variety is considered more correct than another. Editors should understand that the differences between the varieties are largely superficial. Cultural clashes over spelling and grammar can be avoided by using the following four guidelines. (The accepted style of punctuation is covered in the punctuation section, above.)

Consistency within articles

See also Internal consistency

Each article should consistently use the same conventions of spelling, grammar, and punctuation. For example, these should not be used in the same article: center and centre; color and colour; em dash and spaced en dash (see above). The exceptions are as follows:

  • quotations (retain the original variety of the quotation even if it differs from that of the article; though the precise styling of punctuation marks such as dashes, ellipses, apostrophes, and quotation marks should be made consistent with the surrounding article);
  • proper names (use the original spelling, for example United States Department of Defense and Australian Defence Force);
  • book titles (again, use the original spelling—if there are multiple editions which spell a given title differently, use the one consulted); and
  • explicit comparisons of varieties of English.

Strong national ties to a topic

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WP:TIES

An article on a topic that has strong ties to a particular English-speaking nation uses the English of that nation. For example:

This avoids articles being written in a variety that is inappropriate for the great majority of its readers. For example, Australians reading the article Australian Defence Force or Americans reading American Civil War should not stumble over spellings or constructions not used in their own variety of English.

In a biographical or critical article, it may be best to use the subject's own variety of English (where there is a definite preference), especially if the author's writings are quoted in the article. For example, avoid American English commentary on quotations from Tolkien's very British prose.

Retaining the existing variety

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If an article has evolved using predominantly one variety, the whole article should conform to that variety, unless there are reasons for changing it based on strong national ties to the topic. In the early stages of writing an article, the variety chosen by the first major contributor to the article should be used. Where an article that is not a stub shows no signs of which variety it is written in, the first person to make an edit that disambiguates the variety is equivalent to the first major contributor.

Opportunities for commonality

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WP:VNE

Wikipedia tries to find words that are common to all varieties of English.

  • Universally used terms are often preferable to less widely distributed terms, especially in article names. For example, fixed-wing aircraft is preferred to the national varieties fixed-wing aeroplane (British English) and fixed-wing airplane (American English).
  • If one variant spelling appears in an article name, redirect pages are made to accommodate the other variants, as with Artefact and Artifact, so that all variants can be used in searches and in linking.
  • Terms that are uncommon in some varieties of English, or that have divergent meanings, may be glossed to prevent confusion. Insisting on a single term or a single usage as the only correct option does not serve the purposes of an international encyclopedia.
  • Use an unambiguous word or phrase in preference to one that is ambiguous because of national differences. For example, use alternative route (or even other route) rather than alternate route, since alternate may mean only "alternating" to a speaker of British English.

Articles such as English plural and American and British English differences provide information on the differences between these major varieties of the language.

Identity

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MOS:IDENTITY
  • Disputes over how to refer to a person or group are addressed by policies such as Verifiability, Neutral point of view, and Article titles where the term appears in the title of an article. When there is no dispute, the term most commonly used for a person will be the one that person uses for himself or herself, and the most common terms for a group will be those that the group most commonly uses for itself. Wikipedia should use them too. (See for example the article Jew, which demonstrates that most Jews prefer that term to "Jewish person".)
  • Any person whose gender might be questioned should be referred to using the gendered nouns, pronouns, and possessive adjectives that reflect that person's latest expressed gender self-identification. This applies when referring to any phase of that person's life. Nevertheless, avoid confusing or seemingly logically impossible text that could result from pronoun usage (for example: She fathered her first child).
  • Use specific terminology. For example, often it is more appropriate for people from Ethiopia (a country in Africa) to be described as Ethiopian, not carelessly (with the risk of stereotyping) as African.
  • The term Arab (never to be confused with Muslim or Islamic) refers to people and things of ethnic Arab origin. The term Arabic refers to the Arabic language or writing system, and related concepts (Not all Arab people write or converse in Arabic).
  • As always in a direct quotation, use the original text, even if the quoted text is inconsistent with the preceding guidelines.

Foreign terms

Foreign words should be used sparingly.

No common usage in English
Use italics for phrases in other languages and for isolated foreign words that are not current in English.
Common usage in English
Loanwords and borrowed phrases that have common usage in English—Gestapo, samurai, vice versa, esprit de corps—do not require italics. A rule of thumb is not to italicize words that appear unitalicized in major English-language dictionaries.
Spelling and romanization

Names not originally in a Latin alphabet—such as Greek, Chinese, or Cyrillic scripts—must be romanized into characters generally intelligible to English-speakers. Do not use a systematically transliterated or otherwise romanized name if there is a common English form of the name, such as Tchaikovsky or Chiang Kai-shek.

The use of diacritics (accent marks) on foreign words is neither encouraged nor discouraged; their usage depends on whether they appear in verifiable reliable sources in English and on the constraints imposed by specialized Wikipedia guidelines. Place redirects at alternative titles, such as those without diacritics.

Spell a name consistently in the title and within the article (covered in Article titles), unless there is a good reason to use an alternative, such as may be given in Naming conventions (use English). For foreign names, phrases, and words generally, adopt the spellings most commonly used in English-language references for the article, unless those spellings are idiosyncratic or obsolete. If a foreign term does not appear in the article's references, adopt the spelling most commonly used in other verifiable reliable sources (for example other English-language dictionaries and encyclopedias). If a term appears rarely in English, an available alternative may be better.

Sometimes the usage will be influenced by other guidelines such as National varieties of English, above, which may lead to different choices in different articles.

Images

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MOS:IMAGES
  • Start an article with a right-aligned lead image or infobox.
  • Images should be inside the section they belong to (after the heading and after any links to other articles), and not above the heading.
  • Avoid sandwiching text between two images that face each other.
  • Use captions to explain the relevance of the image to the article (see Captions, below).
  • See this tutorial for how to group images and avoid "stack-ups".
  • It is often preferable to place images of faces so that the face or eyes look toward the text. Multiple images in the same article can be staggered right-and-left (for example: Timpani). However, images should not be reversed simply to resolve a conflict between these guidelines; doing so misinforms the reader for the sake of our layout preferences. An image should be reversed or substantially altered only if this clearly assists the reader (for example, cropping a work of art to focus on a detail discussed in the text). Any such alteration must be noted in the caption.
  • The thumbnail option may be used ("thumb"), or another size may be fixed. The default thumbnail width is 220 pixels; users can adjust this in their preferences. An option such as "|300px|" resizes the image to the specified width in pixels, and "upright=1.2" (or "|frameless|upright=1.2" for plain pictures) resizes an image to approximately the given multiple of a user's preferred width. An image should generally be no more than 500 pixels tall and 400 pixels wide, so it can be comfortably displayed next to the text on the smallest monitors in common use; an image can be wider if it uses the "center" or "none" options to stand alone. The {{Wide image}} and {{Tall image}} templates display images that would otherwise be unreasonably wide or tall. Examples where adjusting the size may be appropriate include, but are not limited to, the following:
  • Lead images, which should usually be no wider than "300px" ("upright=1.35").
  • Images in which detail is relatively unimportant (for example, a national flag), and which may need smaller sizes than usual.
  • Images containing important detail (for example, a map, diagram, or chart), and which may need larger sizes than usual.
  • Images in which a small region is relevant, but cropping to that region would reduce the coherence of the image.
  • Use {{Commons}} to link to more images on Commons, wherever possible. The use of galleries should be in keeping with Wikipedia's image use policy.
  • Editors are encouraged to add alt text to all images for which it seems reasonable, including math-mode equations. Alternative text describes the image for readers who cannot see the image, such as visually impaired readers or those using web-browsers that do not download images.
    • Instructions on adding alt text to equations and images can be found here. The Altviewer tool displays an article's alt text.
    • Alt text is not the same as captions: alt text describes the image for those who cannot see it, whereas captions are intended to explain or supplement an image for all readers. Therefore, alt text should not repeat the caption or other nearby text. Purely decorative images need not have alt text; editors should ask themselves how much sighted readers would lose if the picture were blanked, and how far that is describable in words.

Avoid entering textual information as images

Textual information should be entered as text rather than as an image, unless there is a good editorial reason for doing otherwise. True text may be colored and decorated with CSS tags and templates, but text in images cannot be. Images are not searchable, are slower to download, and are unlikely to be read as text by devices for the visually impaired. Even if some of these problems can be worked around, as by including a caption or alt text, editors should still consider whether an image of text really adds anything useful. Any important textual information in an image should also appear in the image's alt text, caption, or other nearby text.

Captions

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MOS:CAPTIONS

Use of captions

Photographs and other graphics should always have captions, unless they are "self-captioning" (such as reproductions of album or book covers) or when they are unambiguous depictions of the subject of the article. For example, in a biography article, a caption is not mandatory for a portrait of the subject pictured alone, but might contain the name of the subject and additional information relevant to the image, such as the year or the subject's age.

Formatting of captions

  • Captions normally start with a capital letter.
  • Most captions are not complete sentences, but merely nominal groups (noun phrases, sentence fragments) that should not end with a period. If a complete sentence occurs in a caption, that sentence and any sentence fragments in that caption should end with a period.
  • Captions should not be italicized, except for words that are conventionally italicized.
  • Captions should be succinct; more information about the image can be included on its description page, or in the main text.

Bulleted and numbered lists

  • Do not use lists if a passage reads easily using plain paragraphs.
  • Do not leave blank lines between items in a bulleted or numbered list unless there is a reason to do so, since this causes the Wiki software to interpret each item as beginning a new list.
  • Use numbers rather than bullets only if:
    • a need to refer to the elements by number may arise;
    • the sequence of the items is critical; or
    • the numbering has some independent meaning, for example in a listing of musical tracks.
  • Use the same grammatical form for all elements in a list, and do not mix the use of sentences and sentence fragments as elements.
    • When the elements are complete sentences, they are formatted using sentence case and a final period.
    • When the elements are sentence fragments, they are typically introduced by a lead fragment ending with a colon. When these elements are titles of works, they retain the original capitalization of the title. Other elements are formatted consistently in either sentence case or lower case. Each element should end with a semicolon, with a period instead for the last element. Alternatively (especially when the elements are short), no final punctuation is used at all.

Links

Wikilinks

Make links only where they are relevant to the context: It is not useful and can be very distracting to mark all possible words as hyperlinks. Links should add to the user's experience; they should not detract from it by making the article harder to read. A high density of links can draw attention away from the high-value links that you would like your readers to follow up. Redundant links clutter the page and make future maintenance harder. (An example of a redundant link: the tallest people on Earth)

Check links: After linking, ensure that the destination is the intended one; many dictionary words lead to disambiguation pages and not to complete articles on a concept. An anchor into a targeted page—the label after a pound sign (also called "hash sign": #) in a URL—will get readers to the relevant area within that page.

Initial capitalization: Wikipedia's MediaWiki software does not require that wikilinks begin with an upper-case character. Only capitalize the first letter where this is naturally called for, or when specifically referring to the linked article by its name: Snakes are often venomous, but lizards only rarely (see Poison).

External links

External links should not normally be used in the body of an article. Articles can include an external links section at the end to list links to websites outside Wikipedia that contain further information, as opposed to citing sources. The standard format is a primary heading named == External links == followed by a bulleted list of links. External links should identify the link and briefly indicate its relevance to the article subject. For example:

*[http://history.nih.gov/exhibits/history/index.html History of NIH]
*[http://www.nih.gov/ National Institutes of Health homepage]

These will appear as:

Avoid listing an excessive number of external links; Wikipedia is not a link repository.

Miscellaneous

Keep markup simple

Use the simplest markup to display information in a useful and comprehensible way. Markup may appear differently in different browsers. Use HTML and CSS markup sparingly and only with good reason. Minimizing markup in entries allows easier editing.

In particular, do not use the CSS float or line-height properties because they break rendering on some browsers when large fonts are used.

Formatting issues

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WP:MOSCOLOR

Formatting such as font size, blank space, and color are issues for the Wikipedia site-wide style sheet and should not be set in articles except in special cases. If you absolutely must specify a font size, use a relative size like font-size: 80%, not an absolute size like font-size: 8pt. It is almost never a good idea to use other style changes, such as font family or color.

Typically, the use of custom font styles will:

  • reduce consistency, since the text will no longer look uniform;
  • reduce usability, since it will probably be impossible for people with custom stylesheets (for accessibility reasons, for example) to override it, and it might clash with a different skin as well as inconvenience people with color blindness; and
  • increase arguments, since other Wikipedians may disagree aesthetically with the choice of style.

Color coding

Do not use color alone to convey information (color coding). Such information is not accessible to people with color blindness, on black-and-white printouts, on older computer displays with fewer colors, on monochrome displays (PDAs, cell phones), and so on.

When conveying information via colors, choose colors that are unambiguous (such as maroon and teal) when viewed by a person with red-green color blindness (the most common type). Any information conveyed via shades of red and green should also be conveyed in some other way. Viewing the page with Vischeck can help determine whether the colors should be altered.

It is certainly desirable to use color as an aid for those who can see it, but the same information should still be accessible without it.

Scrolling lists and collapsible content

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MOS:COLLAPSE

Scrolling lists and boxes that toggle text display between hide and show are acceptable for use, but should not be used in article prose. This includes reference lists, image galleries, and image captions; they especially should not be used to conceal 'spoiler' information (see Wikipedia:Spoiler). Collapsible sections are useful in navboxes, infoboxes, or to consolidate information already covered in prose. When scrolling lists or collapsible content are used, care should be taken to ensure that the content will still be accessible on devices which do not support JavaScript and/or CSS.

Invisible comments

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WP:COMMENT

Editors use invisible comments to communicate with each other in the body of the text of an article. These comments are visible only in the wiki source (that is, in edit mode), not in read mode.

Invisible comments are useful for flagging an issue or leaving instructions about part of the text, where this is more convenient than raising the matter on the talk page. They should be used judiciously, because they can clutter the wiki source for other editors. Check that your invisible comment does not change the formatting, for example by introducing extra or unwanted white space in read mode.

To leave an invisible comment, enclose the text you intend to be read only by editors between <!-- and -->. For example: <!--If you change this section title, please also change the links to it on the pages ...-->.

Pronunciation

Pronunciation in Wikipedia is indicated using the International Phonetic Alphabet (IPA). In most situations, for ease of understanding by the majority of readers and across variants of the language, quite broad IPA transcriptions are best for English pronunciations. See Wikipedia:IPA for English and Wikipedia:IPA (general) for keys, and {{IPA}} for templates that link to these keys. For English pronunciations, pronunciation respellings may be used in addition to the IPA.

Blazon

For heraldic terms written in Anglo-Norman (a form of Middle English), refer to WP:BLAZON. The key points are:

  • Anglo-Norman blazons should be put in italics.
  • Short extracts may be put in-line but longer ones should be indented on a new line (similar to quotations).
  • Tinctures should not be capitalized unless the first word of a blazon, except Or to distinguish it from the conjunction or. Charges need not be capitalized.
  • Tinctures may be repeated (Or, on a bend gules a sword Or) or truncated (Or, on a bend gules a sword of the first), as it appears in the source.
  • Exceptions should be made if these are more appropriate for a particular blazon.

See also

Notes

Style guides on other Wikimedia projects

Further reading

Wikipedians are encouraged to familiarize themselves with other guides to style and usage, which may cover details that are not included in this Manual of Style. Among these are: