But that's not all. Some ISPs run caching servers, machines that store frequently-viewed webpages so that users access them locally rather than across the net. An ISP's caching server could give the police a profile of what web pages the users have been browsing. I'm not trying to scare anyone. My point is that sharing information on the Internet is a two-way street.
Computers keep extensive records.
Using the Internet often means you leave a trail behind you. This is part of life in the digital age. Every time you use a credit card you create a record in several computers. Other computers may be storing information about you such as your medical history, driving record, tax filings and so on. This means citizens in the digital age should know their rights.