http cookie

HTTP cookie
computer cookie

   <World-Wide Web> A system invented by {Netscape} to allow a
   {web server} to send a {web browser} a packet of information
   that will be sent back by the browser each time it accesses
   the same server.  Cookies can contain any arbitrary
   information the server chooses to put in them and are used to
   maintain {state} between {HTTP} {transactions}, which are
   otherwise stateless.  Typically this is used to authenticate
   or identify a registered user of a {website} without
   requiring them to sign in again every time they access it.
   Other uses are, e.g. maintaining a "shopping basket" of goods
   you have selected to purchase during a session at a site, site
   personalisation (presenting different pages to different
   users) or tracking which pages a user has visited on a site,
   e.g. for marketing purposes.

   The browser limits the size of each cookie and the number each
   server can store.  This prevents a malicious site consuming
   lots of disk space.  The only information that cookies can
   return to the server is what that same server previously sent
   out.  The main privacy concern is that, by default, you do not
   know when a site has sent or received a cookie so you are not
   necessarily aware that it has identified you as a returning
   user, though most reputable sites make this obvious by
   displaying your user name on the page.

   After using a shared login, e.g. in an {Internet cafe}, you
   should remove all cookies to prevent the browser identifying
   the next user as you if they happen to visit the same sites.

   Cookie Central (http://cookiecentral.com/c_concept.htm).

   (2004-08-26)