When the user accesses the web site again, the server gets access to the information the server had originally saved. One of the limitations of cookies is that it is browser-dependent, and enables only limited information about the web user. Filtering An interesting source of demographic data is from collaborative filtering environments in the Web. An example of such a site is firefly . This site provides ways that users can view sites that are recommended by other members, and recommend different sites to each other.
Members can also provide information about themselves through web pages.
Such collaborative systems are a gold mine of information as not only do they provide user profiles, they also shows users' interests, tastes and preferences in web sites. A few ideas have been proposed for alternative or complementing ways to user surveys. One proposal is that the user agent, i.e. a client, sends a randomly generated sessionID at the beginning of each HTTP session. That sessionID is then monotonically increased at each request in that session. This will allow the server to track the information that is being requested by the client.