What is happening?
Google is tearing up more than 60 privacy policies for and array of services, from search, to Gmail, to Google Maps, to YouTube and much more besides, and replacing them with a single "simplified" policy. At the same time it's is combining all the data each of the services hold on their users to create a single, detailed profile of hundreds of millions of people's interests.
Why is Google doing this?
It says the new policy will be easier for users to understand. That's doubtless true, but the motivation behind it is financial. Google makes its money from online advertising, and online advertising is worth more if it is targeted to individual users interests, because they are more likely to click on ads that appeal to their interests.
By combining more than 60 files to create a single master profile of each user, Google will be able to more closely track their interests and in more detail, and use data gathered by one service to target advertising on another. For instance, if you spend an hour watching fitness videos on YouTube and then visit your Gmail account, you may be served ads from Nike or Adidas alongside your emails.
Am I affected?
Given you use the web, almost certainly. Google's search service is almost completetly dominant in Britain, Gmail is the leading free email service and YouTube by far the biggest video website. Even if you previously only had a Gmail account, and did not log in to other Google website, the data they collect will now be addeed to you master profile.
Can it be stopped?
Not now. The changes come into force today, and Google has resisted appeals from both American and European authorities to halt the project. It could however still cause serious trouble for the firm; the French data protection watchdog, on behalf of other European regulators including Britain's Information Commisioner, has said it has "strong doubts" whether the new policy is lawful.
What can I do?
Google has been warning users about the changes for more than a month, but most of them have ignored it.
The nuclear option is to delete all your data an close down your Google accounts. Short of that, there are some changes you can make to your settings that will reduce how much data about you Google holds and uses, such as deleting your "Web History" file, opting out of personalised advertising and creating separate Google accounts for its various services. Read The Telegraph's guide.
