High-speed, business-quality Internet connections can be expensive. While some companies try to regulate personal use of the corporate Internet connection, that can be difficult. Many use the Internet in their work. For those who allow employees to access the Internet during their free time (e.g., during the lunch hour), they may find employees overloading the connection. Some may abuse the connection for their own purposes, such as by downloading music or movies.
Whatever the cause, anything that can reduce the overall demand on a high-speed Internet connection can save significant amounts of money. A proxy server can help you reduce the load on your Internet connection, caching data commonly accessed from the Internet, and regulating access to unwanted sites, such as those with "sex" in the URL.
The standard open source method for regulating Internet connections in this way is the Squid Web Proxy Cache, documented at http://www.squid-cache.org. Commercial support for Squid is available through ViSolve, at http://squid.visolve.com/squid/. If you want the full capabilities of Squid, with content filtering, you'll also want to install SquidGuard, which is a combined filter, redirector, and access controller plug-in (http://www.squidguard.org).
Squid supports the use of multiple computers; load from one client can be sent to a cache_peer parent or sibling computer, also configured as a Squid proxy server.