while navigating the world wide web, a "user agent" (web browser) makes requests to another computer, known as a web server, every time the user selects a hyperlink. most web servers store information about the sequence of links that a user "clicks through" while visiting the websites that they host in log files for the site operator's benefit. the information of interest can vary and may include: information downloaded, webpage visited previously, webpage visited afterwards, duration of time spent on page, etc. the information is most useful when the client/user is identified, which can be done through website registration or record matching through the client's internet service provider (isp). storage can also occur in a router, proxy server or ad server.