From Wikipedia, the free encyclopedia.
A proxy server is a computer network service which allows clients to make indirect network connections to other network services. A client connects to the proxy server, then requests a connection, file, or other resource available on a different server. The proxy provides the resource, possibly by connecting to the specified server, or by serving it from a cache. In some cases, the proxy may alter the client's request or the server's response for various purposes.
A common proxy application is a caching Web proxy. This provides a nearby cache of Web pages and files available on remote Web servers, allowing local network clients to access them more quickly or reliably.
When it receives a request for a Web resource (specified by a URL), a caching proxy and looks for the resulting URL in its local cache. If found, it returns the document immediately. Otherwise it fetches it from the remote server, saves a copy in the cache and returns it to the requester. The cache will usually have an expiry algorithm which flushes documents according to their age, size, and access history.
Web proxies can also filter the content of Web pages served. Some censorware applications -- which attempt to block offensive Web content -- are implemented as Web proxies. Network operators can also deploy proxies to intercept computer viruses and other hostile content served from remote Web pages.