A proxy server node intercepts data requests from a client, retrieves the requested information from content-hosting machines, and delivers that content back to the client. Most commonly, the requests are for documents stored on Web server machines and delivered via the Hypertext Transfer Protocol (HTTP). However, some proxy servers also handle other protocols such as File Transfer Protocol (FTP) and Gopher. The IP address of the content-hosting machines is not seen by the clients.
A caching proxy node stores cacheable content in a local cache before delivering it to the client. Subsequent requests for the same content are served from the local cache which is much faster and does not consume as much content server processing and network bandwidth.