Question: What is a Cookie?

Answer: A cookie (also known as a "Persistent Client State HTTP Cookie") is a small data text file that is transferred from a World Wide Web server computer to a client computer during a World Wide Web browsing session. The cookie is stored on the recipient computer and sent back to the server computer whenever an HTML file request is made. The cookie can be configured to last for only a single browsing session, or it can be configured to be stored on the client computer's hard drive for subsequent sessions. The cookie can include data such as the time of the client computer's last HTML file request from the server or the user name and password that the server assigned to the client computer.

With such information, a cookie can be used to personalize a World Wide Web site for each visitor by sending the server a list of the user's selected preferences during an earlier visit. A cookie can also permit a web server to track which web pages of its World Wide Web site were viewed during the client computer's last visit.

A cookie's primary purpose is to save and transmit information about a client computer to a server computer. At first impression, it may appear that transmission of such information results in a loss of privacy. It should be clarified, however, that a cookie is generated by the server computer based upon information the server already has regarding the client computer, and it is not designed to transfer additional information to the server from the client computer's RAM or hard drive. Further, as a security measure each cookie is designed to be read only by the server that originated it.

Cookies can do a great deal to enhance a browsing experience. Nevertheless, if a user does not have a taste for cookies, most popular browser programs can be configured to give the choice of whether to accept them.

Additional information regarding cookies can be found in Netscape Communications Corporation's home page.

Questions may submitted to James Black by e-mail at
© James R. Black 1997
applet by New Media Marketing Lab at Sun Microsystems, Inc.