One blogger from tech site Mashable found this week that Google's Ad Preferences page assume that she was middle-aged - and a man, simply because her interests included technology and computing.
The profile page, called Ad Preferences, is hidden away inside a settings menu in Google Accounts, but can be accessed directly here.
This sort of in-depth profiling raises alarm bells with privacy activists. 'Consumers have increasingly digital lives and they are developing an unfathomably large data trail every day,' says Rainey Reitman, activism director for privacy group Electronic Frontier Foundation. 'There has never been another time in history where privacy was under the kind of assault it is today.'You can opt out of the tracking, or manually edit your details. Google also does not store information on controversial subjects such as pornography. The Ad preferences page came to public attention following a sweeping change to 'privacy policy' which comes into effect on March 1, although the preferences page was launched some time ago. YouTube data, Gmail information and search data will all be used to build up ever more accurate advertising profiles and also the company claims it will make searches more personalised.