Netscape introduced the “cookies” specification with Navigator Version 2.0. The original purpose of cookies was to make it possible for a web server to track a client through multiple HTTP requests. This sort of tracking is needed for web-based applications. For example, an online catalog might store a session ID in a cookie so that the web server can keep track of what items are in a customer’s “shopping cart.”
A cookie is a block of ASCII text that a web server can pass into a user’s instance of Netscape Navigator (and many other web browsers). Once received, the web browser sends the cookie every time a new document is requested from the web server.
Cookies are kept in the web browser’s memory. If a cookie is persistent, the cookie is also saved by the web browser. Persistent cookies can be used to store a user’s preferences for things like screen color, so that the user does not need to re-register preferences each time he or she returns to a web site.
Netscape browsers store cookies in the file called
cookies.txt, which can be found in the
user’s preference directory. Internet Explorer saves cookies in
the directory C:\Windows\Cookies on Windows
Netscape’s cookies can be used to remove anonymity on the web or to enhance it. Unfortunately, the choice is not in the hands of the web user: it is under the control of the web server. Furthermore, it can be difficult for users to tell to what purpose cookies are being used.