What is a proxy server?
Proxy server is a computer that sits between a client computer and a real
server, and provide indirect network services to a client. A proxy server
intercepts all client requests, and provide responses from its cache or
forward the request to the real server.
Proxy servers are used for a few purposes. If it is used as a caching
web proxy, it can dramatically improve performance of a web response. When
a request is made by a client, a caching proxy returns response directly
from its cache if the document exists. Otherwise, it makes the request
to the real server, returns the result, and save it in its cache for later
Proxy servers may also be used as a web proxy to filter web page contents.
An organization or company may use a proxy server to block offensive web
contents from viewed by the users. Internet Service providers may also
use proxies to block computer viruses and other offensive contents.
With organizations deploying proxy servers to block its users from accessing
specific websites such as myspace.com, users may also use web proxy to
access those blocked sites indirectly. Those web proxies are built with PHP
or CGI to implement the proxying functionality, and provide web access to
those sites blocked by corporation and school proxies.