A cookie is a small piece of data which is sent from a web server to a web browser and stored locally on the user’s machine. The cookie is stored on the user’s machine but is not an executable program and cannot do anything to the machine. Whenever a web browser requests a file from the same web server that sent the cookie, the browser sends a copy of that cookie back to the server. Some cookies may use a unique identifier that links to information such as logon or registration data, online “shopping cart” selections, user preferences, Web sites a user has visited, et cetera.