Who's collecting your data?
From 25 May 2011, the methods used by websites to track visitors and tailor ads to their behaviour will change as European laws (EU’s Privacy and Electronic Communications Directive) dictate that "explicit consent" must be gathered from web users who are being tracked via text files: "cookies", which are widely used to help users navigate faster around sites they visit regularly.
The changes are demanded by the European e-Privacy directive which comes into force in the UK in May. It is widely accepted that the section of the directive dealing with cookies was drawn up in an attempt to protect privacy and, in particular, limit how much use could be made of behavioural advertising.
The IAB has created a site that explains how behavioural advertising works and lets people opt out of it.