For this reason, the Web page server has no memory of what pages it has sent to a user previously or anything about your previous visits. A cookie is a mechanism that allows the server to store its own file about a user on the user's own computer. The cookie subdirectory will contain a cookie file for each Web site you've been to that uses cookies. Cookies are commonly used to rotate the banner ads that a site sends so that it doesn't keep sending the same ad as it sends you a succession of requested pages. They can also be used to customize the pages they send you based on your browser type or other information you may have provided the Web site.
Web users can prohibit the creation of cookies by setting the appropriate browser preferences.