Cookies are small text files placed on your hard drive by Web sites you visit. Basic cookies contain a special code that identifies, by that code only, the PC on which it is stored.
Webmasters use cookies primarily to identify visitors.
Among other things, that helps them spot return visitors, how many times they return, and how they move around the site. That helps Webmasters sharpen their sites' appeal. Many Internet surfers repeatedly visit Web sites they have individualized to display information important to them. Some Webmasters control access to their sites, or to specific areas, by requiring the surfer to obtain a user ID and a password. These may also be stored in cookies to make it easier for regulars to gain faster access to the restricted areas.