Google's ads follow you online
Updated on 08 April 2009
Google unveils new plans to trace the internet sites you visit to send out targeted advertising.
The search and online advertising giant Google will today begin collecting data for its controversial new service that targets adverts based on the previous websites that internet users have visited.
The idea has been trialled for the last month on its own services, and today is being extended to hundreds of thousands of other sites where Google sells advertising. But critics say the information should not be collected without the explicit consent of web users.
Our technology correspondent Benjamin Cohen explains how the system works.
