A proxy server receives a request for an Internet service such as a web page request from a user. If it passes the filtering requirements the proxy server assumes it is also a cache server and looks in its local cache of previously downloaded web pages. If it finds the page, it returns it to the user without needing to forward the request to the Internet. If the page is not found, the proxy server acts as a client on behalf of the user and uses its own IP address to request the web page from the Internet. An advantage of using a proxy server is that because one or more Internet sites are frequently requested, they are likely to be in the proxy's cache, which improves response time.

It caches information on a Web server and acts as an intermediary between a Web client and that Web server. It basically holds the most commonly and recently used content from the World Wide Web for users in order to provide quicker access and to increase server security. This is common for an ISP especially if it have a slow link to the Internet. Proxy server is also constructs that allow direct Internet access from behind a firewall. It opens a socket on the server, and allow communication via that socket to the Internet. For example, if your computer is inside a protected network, and you want to browse the Web using Netscape, you would set up a proxy server on a firewall. The proxy server would be configured to allow requests from your computer, trying for port 80, to connect to its port 1080, and it would then redirect all requests to the proper places.