There is one important exception, however. When a web server responds to a request for a document, it may send, packaged together with the document, a small file called a "cookie." If cookie caching has been enabled on the client's browser, then that cookie will be saved in a special directory on the client's hard drive. Later, when the user decides to return to the web site from which the cookie originated, the cookie will be automatically sent in conjunction with the HTTP request. Thus, the server is able to store, on the client's machine, persistent "state information" about the user's recent activity on the remote web site.