What are cookies anyway?
A cookie is really a text string that is transmitted as part of an HTTP header when needed. It is usually stored in memory under the control of the browser. There is an expiration time for each cookie. If the expiration of the cookie is after the time the user leaves a site, the information is written to a text file on the user’s machine in a pre-defined location specified by the browser. Cookie entries are limited in length. The number of cookies that can exist on a machine is also restricted.