1. A block of data that a server returns to a client in response to a request from the client.
2. On the World Wide Web, a block of data that a Web server stores on a client system. When a user returns to the same Web site, the browser sends a copy of the cookie back to the server. Cookies are used to identify users, to instruct the server to send a customized version of the requested Web page, to submit account information for the user, and for other administrative purposes.
3. Originally an allusion to fortune cookie, a UNIX program that outputs a different message, or “fortune,” each time it is used. On some systems, the cookie program is run during user logon.
The most common meaning of Cookie on the Internet refers to a piece of information sent by a Web Server to a Web Browser that the Browser software is expected to save and to send back to the Server whenever the browser makes additional requests from the Server.