An anonymous proxy server is a type of online computer server that can act as middleman for web browsing and various other Internet-based activities. These servers are typically accessed through web browsers, though it is also possible to alter a computer, router or modem to send requests directly to a proxy. In either case, the anonymous proxy server fields requests, forwards them to the proper web servers and then passes on the requested data. If an anonymous proxy is configured correctly, a web server will see only the proxy and retain no record of the computer that made the original request. This can be useful for retaining some measure of privacy, though in some cases proxy servers can also be used to access region-locked content.
There are a number of different types of proxies, though only a few can offer any sort of anonymity. Most proxies pass on the Internet protocol (IP) addresses of computers that make requests through them. These transparent proxies can be used for certain purposes, such as circumventing IP bans. It is sometimes possible to set up this kind of proxy to reach sites and content that a school or business has restricted access to. In order to create any sort of privacy though, it is necessary to make use of an anonymous proxy server.
The most basic type of anonymous proxy server readily identifies itself as such but does not pass on the IP information of any computer that makes requests through it. This can allow websites to be accessed without leaving any external evidence that a particular computer visited them. Instead of retaining the IP of the computer that made the requests, a website will instead have a record of the proxy that actually made the connection. This kind of anonymous proxy server can sometimes be used to access region-locked content, though more advanced versions are sometimes required.
Other proxies that can offer higher levels of privacy are sometimes known as distorting and high anonymity servers. Distorting proxies identify themselves as proxy servers when making requests, but instead of sending no IP address they report an incorrect one. In some cases this may be required to access certain region-locked content. High anonymity servers can also be of use in some cases, since they are not even identifiable as proxies. In addition to not identifying themselves as proxies when sending requests, they also refuse to pass on any IP information.