A proxy server is a computer network service that allows clients to make indirect network connections to other network services. It lies between a client application, for example, a Web browser, and a real server. All requests which are sent to the main server pass through a proxy server which checks whether it can fulfill such requests itself. If it cannot satisfy the request itself, it forwards it to the real server.
Proxy servers are useful in two ways. In the first place, it can save a considerable amount of time and improve performance for groups of users. It saves the results of all requests for a certain period of time. Thus, if a fresh request comes for the Web page which was accessed through a previous request during such period, it can immediately fulfill the request by opening the page without forwarding the request to the real server. Secondly, proxy servers also filter requests to block or disallow certain outgoing or incoming requests to the real server.
