Some Web sites use cookies to track repeat visits of individuals to monitor Web site usage. Other sites use cookies to identify users so they don't have to log in every time they visit the site. The benefit of cookies is that they can be used to personalize content to meet the needs of a specific user. The Web site may deliver one or more cookies to the client. The client stores cookie data on its local hard drive.
Cookies can only store data that is provided by the server or generated by an explicit user action.
Cookies cannot be used to gather sensitive information such as the fields in a Netscape preference file. Cookies are passive data structures that are delivered to the client, stored on the client's hard drive, and returned in certain situations to the same server that provided the information in the first place. The file name is different for each platform. Client state information can be stored in several ways. For example, server administrators and programmers can create a database application that tracks and stores data they would otherwise have managed with cookies.