There are three main types of proxy servers, each of which performs the same basic function of acting as an intermediary between a client computer and a web server. Regular caching proxy servers and transparent proxies are both intended to speed up performance by holding on to requested data. This caching process can result in data being delivered more quickly if it is requested repeatedly. Reverse proxies also work by caching static data, though they are typically part of a server infrastructure and are intended to take some load off a a web server. Most proxy servers pass the client's Internet protocol (IP) address and other information, though there are anonymous proxies that can hide this information.
Traditional proxy servers are intended to cache commonly requested data to speed up an end user's Internet browsing experience. These servers are typically set up manually by instructing the web browser on a machine to direct requests to the proxy. Each time the browser makes a request, the proxy server checks its cache to see if it has the required information. If it does, that data is delivered at a speed that is typically faster than it would be to download directly from the web server.
Transparent proxies work in much the same way but do not require any client side configuration. The web browsers on each client machine send requests and receive data without being aware that the information is passing through a proxy. Many large businesses use transparent proxies to avoid manually configuring each client, and Internet service providers (ISPs) often use them as well. When an ISP makes use of a transparent proxy, it can effectively decrease the time it takes users to download commonly accessed sites.
The third main type of proxy server reduces the load experienced by a web server, rather than improving performance for the end user. These reverse proxies are typically integrated into the server architecture and can handle many requests for static information, such as images and videos. Any information that is generated dynamically is still sent directly from the web server to the client, though offloading static data can improve performance.
Each of these types of proxy servers typically forward any client information along with the requests for data. If a user wants to hide his IP or other personal information, a special anonymous proxy server has to be used. These servers operate in the same way as other proxies, but they do not record or pass on personal information. Anonymous proxy servers can be traditional caching proxies that a web browser has to be configured to use, or they may be accessed through a website interface.