It's known as 'communications data' and inline with European directives the UK Government has proposals for a giant database containing all internet and telephone traffic. Currently, details of the times, dates, duration and locations of mobile phone calls, numbers called, websites visited and addresses e-mailed are already stored by telecommunications companies for 12 months under a voluntary agreement. Under the new proposal this information would be kept for two years by law and may be held centrally on a searchable database. 

I'm not going to stray into the political minefield that this move conjures up suffice to say that George Orwell would surely see more than a little resemblance of his Ministry of Truth in the present day Home Office's justifications and ramblings. Let's just hope they don't leave a copy of that database lying around.