Many work places and schools are cracking down on the web sites and online services that are made available in their buildings. Since circumventors are used to bypass censors in computers, web sites like Orkut, MySpace, Bebo, Xanga, Silkroad Online, YouTube, Miniclip, Facebook, Gaiaonline and other non-work or school related social web sites have become targets of mass banning.
Proxy Web server creators have become more clever allowing users to encrypt links, and any data going to and from other web servers. This allows users to access websites that would otherwise have been blocked.
A special case of web proxies are "CGI proxies". These are web sites that allow a user to access a site through them. They generally use PHP or CGI to implement the proxying functionality. These types of proxies are frequently used to gain access to web sites blocked by corporate or school proxies. Since they also hide the user's own IP address from the web sites they access through the proxy, they are sometimes also used to gain a degree of anonymity, called "Proxy Avoidance".