What They Know About You

By JENNIFER VALENTINO-DEVRIES

A few online marketers will show you what they know about you – or think they know.

Google Inc., Microsoft Corp., Yahoo Inc. and others have created "preference managers" that let you see, and change, the interests they've assigned to you based on your browsing behavior. The companies acted partly in response to concerns about the privacy of the people they're tracking.

Googles Ads Preferences Manager offers a plethora of categories.

Some, but not all, of the preference managers let you halt tracking by that company. But none will block all tracking, or prevent you from seeing ads. Some require you to register, and one lets you pick a charity to which you can donate some of the money made by selling your data.

The companies gather this information by tracking your Web-surfing activity through small computer files or software programs installed on your computer by the websites you visit. Over time, this information says a lot about your interests. Companies then use the information to make other guesses and predictions about you, ranging from gender and age to marital status and creditworthiness.

Some of their guesses can be wrong. Your profile might also be inaccurate if you block or delete cookies, since that prevents companies from following your Web surfing to assess your interests.

Here's where you can go to see what the marketers think they know about you. Some let you correct or delete information already in their database about you, or add more information.

• Google was the most prevalent tracker in The Wall Street Journal's survey of popular websites, with tracking code appearing on 49 of the 50 sites tested. Google's Ads Preferences Manager, at http://www.google.com/ads/preferences/, lets you see the name of the tracking file, or "cookie," it associates with your Web browser and the interests it links to that cookie.

Google's tool lets you remove some interests and add others, choosing from a list ranging from "poetry" to "neuroscience" to "polar regions." You can also disable Google's cookie so it no longer tracks you.

• Microsoft Advertising offers a tool at https://choice.live.com/UserPreferences. It offers 1,295 interests to select, which will influence the ads you see. To change the selections, you must have an account with Hotmail or Windows Live ID. You can opt out of targeted ads from Microsoft without an account.

• Yahoo Inc.'s Ad Interest Manager, which is in testing, shows you the categories in which it thinks you have interests and lets you turn categories off; you can't add interests. Yahoo will also show you what it knows about your computer, including the operating system you are using and your browser, as well as the categories you search and the pages you visit on Yahoo.

You can opt out of interest-based advertising. The tool is at http://privacy.yahoo.com/aim.

Some less well-known companies that serve as middlemen for collecting and disseminating information about Internet users also offer preference managers.

• BlueKai Inc., a "data exchange" where marketers can buy and sell information about people's browsing habits, has a consumer-preferences registry at http://tags.bluekai.com/registry. The registry can include information about where you live, presumed interests and other guesses based on your browsing behavior, such as the kind of job you have and your approximate net worth.

You can remove categories associated with your profile. You can also select a charity that will receive a donation based on advertising sales tied to your data, BlueKai says. You can stop BlueKai from collecting or trading information about you.

• EXelate Media, which bills itself as a marketplace for behavioral-targeting data, provides a preference manager at http://www.exelate.com/new/consumers-optoutpreferencemanager.html. The tool will show categories, such as "Asian Community" or "Casual Gaming," in which eXelate thinks you're interested. You can select the information that you want associated with you and remove what you don't want, or you can opt out of eXelate's program.

• Lotame Solutions Inc., a marketing technology company, lets you remove and add interests. You can indicate your gender and age, or opt out of receiving targeted ads. Its tool is available at http://www.lotame.com/preferences.html.