What anonymity levels of HTTP proxy servers exist?
1. Transparent - these proxies are not anonymous. They don't hide IP-address of a client and let a web server know that you are surfing through a proxy server. The task of such proxies, as a rule, is information caching and/or support of Internet access for several computers via single connection. Such proxies are not applicable for security and privacy while surfing on net. You can use them only for network speed improvement.
2. Anonymous - these proxies don't show your real IP but change the request fields so it is very easy to detect that you are using proxy.
3. High Anonymous - these proxy servers do not pass an IP-address of a client and don't send any variables indicating that you are using proxy server to host and look like real browser.