Cookie is usualy store in webbrowser to identify a user.its a small file that server will place this file to the browser.
Example
To set cookie following function will use
setcookie(“vasanthan”, “mydoubts”, time()+3600);
we can change the expire time.
we can access the cookie value using $_COOKIE[“vasanthan”];//here vasanthan is the name of the cookie
For deleting the cookies use the below function
setcookie(“vasanthan”, “”, time()-3600);//here just giving time as minus value.