There are many angles here to consider.
Web sites keep logs Most web sites keep logs of accesses to their web server.
These logs detail what host you are accessing their site from, and in some cases, the username that is using that host. If you access the web using a graphical browser like Netscape from your office, your hostname is most often your office room number. If you access the web using lynx from hopi, apache, zuni, or navajo or through a graphical browser at home via the slirp program, the host you access it from will be recorded in their logs along with your username. The logs also contain the web pages that you are looking at. The below log records are from our own server.