Cookies help Web sites maintain the user's perferred states.
Cookies are small data files which are delivered to the surfer's machine by the Web site being visited. The Web site may deliver one or more cookies to the client. The surfer stores the cookie data in one or more data files on the surfer's local hard drive. Cookies allow Web sites to maintain specific information on a particular user across HTTP connections. This is similar in many ways to frequent flyer profiles or option settings in desktop software.