It is used to maintain the state of the user at the client system such that the info. can be accessed from the web forms present with in the application.
HttpCookie CookieObject=new HttpCookie(key,value);
Cookies can store string information only.
The default expiration for the Cookies will be 30 Days.
Cookies are browser depended. the values assigned by one browser cannot be write by other browser.
Web browsers are having a capability to block or delete the cookies.