A proxy server is a server (computer system or application) that acts as an intermediary for requests from a client looking for things on another server. The client connects to the proxy server, requests a service (for example, a connection, a file, a web page…) and the proxy server evaluates this request according to its rules.

The concept of a proxy server was invented in the early days of distribution systems, primarily to simplify and control their complexity. Nowadays, most proxy servers serve as so-called web proxies, allowing connections to the WWW (World Wide Web).

Proxy servers have several different uses, including, for example:

• they can provide anonymity to the servers behind them for security reasons
• they can speed up access to resources (through caching)
• they can apply access policies to services and content (for example, to block unwanted sites)
• can access sites that are banned or filtered by a particular ISP or institution
• can bypass security or parental filters
• can bypass internet filters to access sites that are blocked by, for example, the government
• they can monitor the content sent to them and detect malware in time
• they can monitor outgoing content to prevent, for example, data loss