The Internet proxy server is the server that is situated between the client application and an actual server. The Internet proxy server has the role of intercepting every request to the actual server and see if the request can be fulfilled by it. If that is not possible, then it must forward the request to the other server.

If used in an enterprise the Internet proxy server besides the role that it plays in all situations, also have the role of ensuring control and security. This Internet proxy server is linked to a gateway server. This has the role of separating the network of the enterprise from other networks. The Internet proxy server is also associated with a firewall server that is used to protect the network of the enterprise from any intrusions from the outside.

The Internet proxy server receives requests from web pages or any other Internet services from the user. Then if the filtering requirements are passed, the Internet proxy server checks its cache for other downloaded pages( this assuming that the Internet proxy server is a cache server as well ). If the web pages that are required are then found by the Internet proxy server, they are returned to the user. In this case there is no need for the Internet proxy server to forward the request. In case the page can not be found in the cache, then the Internet proxy server must act as a client as thus use its own IP address to request the web page from other servers that are found on the Internet. When the required page is then returned, the Internet proxy server reports it to the initial request and then it is forwarded to the user.

In the users eye, the Internet proxy server seems to be invisible. This is because the request and the response are so quick that the user is under the impression that they are made directly with the Internet server that was addressed. However, this is not the case and the Internet proxy server actually plays a very important part.

There are two main reasons why Internet proxy servers are used. One is to improve the performance and the second to filter the requests. The Internet proxy server can improve the performance for users, because the Internet proxy server actually saves all the requests that the user has made, thus making Internet operations a lot faster. The second reason why Internet proxy servers are used is to filter requests. This operation might be seen in schools or workplaces, where the employees are not allowed to visit certain web sites. This can be very easily done by configuring the Internet proxy server that is used.