"BT will not be prosecuted for snooping on the web browsing habits of its customers.
The Crown Prosecution Service (CPS) has dropped a request bring charges against BT and Phorm - the firm that supplied the monitoring system.
The Webwise software used cookies to track people online and then tailored adverts to the sites they visited.
The CPS explained its decision saying that there was insufficient evidence to proceed with a prosecution".
full story - http://www.bbc.co.uk/news/technology-13015194
Just saying 'The Webwise software used cookies to track people online and then tailored adverts to the sites they visited" rather understates what the system did.
At the same time, it would look for keywords on every site you visited, in order to work out your interests and use this information to tailor its adverts.