A Proxy URL is a web address to access a proxy server through a web browser. With the widespread use of Internet content filters in businesses, schools and even nations around the world, the primary use of proxy servers is to bypass restrictions to certain websites.
Proxy servers are computers that allow client PCs to make indirect network connections to other network services. When a client PC connects to the proxy server, it requests a resource that is available on a different server (usually a file, such as a web page). The proxy then provides the resource to the client by connecting to the specified server, acting as a middle man. In some cases, the resource may even be served to the client from a cache.
There are four main types of proxy servers in use. A transparent proxy identifies itself as a proxy server and makes the original IP address available through HTTP headers. Transparent proxies have the ability to cache websites, but lack the ability to provide anonymity to people who use them. Anonymous proxies identify themselves as proxy servers, but do not make the original IP address available. This type of proxy offers reasonable anonymity for most users, although they are detectable. Distorting proxies get their name from the fact that they make an incorrect original IP address available through HTTP headers for anonymity. A high-anonymity proxy is the only type that does not identify itself as a proxy server. Also, this type does not make the original IP address available, which makes it the most anonymous type.
Proxy servers are used for many different reasons. One of the primary uses of a proxy is to get around blocked content, since many companies and schools use some sort of Internet filter. Some block specific IP address and URLs, while others use keywords to look for in the content of websites. When those keywords are found, the filter identifies it as inappropriate for viewing. The various types of proxies each have advantages and disadvantages for different uses. The use of a transparent proxy will get you around a simple IP ban, but one of the other proxy types is required when anonymity is necessary to access a resource.
In addition to being able to access a proxy through a traditional proxy URL, there is also software widely available that allows Internet users to make use of proxy servers. CGIProxy and PHProxy are popular examples of such software. The customizable features of this software allows users to modify the level of anonymity.
It is a common misconception that proxy servers provide full anonymity, making users completely unable to track. While some servers do provide more anonymity than others, proxies are far from perfect. Those with the right tools and information do still have ways to track the IP of proxy server users. In addition, the use of a proxy by network users may be obvious to those who monitor the network's usage.