How does a proxy server work?

Intermediaries can also implement shared caches that serve more than one person. Proxy caches, also known as forward proxy caches, are usually deployed by internet service providers, schools and corporations to save bandwidth. Interception proxy caches are a variant that doesn't require clients to be explicitly configured to use them. Packages that can be used as a proxy cache include Squid cache, Microsoft Internet Security and Acceleration Server ARA Networks Jaguar 3000 and Blue Coat.