First the basics:
What is a Proxy Server
As defined by RFC 2068, a proxy is "an intermediary program which acts as both a server and a client for the purpose of making requests on behalf of other clients." RFC 2068 continues, "requests are serviced internally or by passing them on, with possible translation, to other servers. A proxy must implement both the client and server requirements of this specification."
The type of a proxy is determined by, among other things, the amount of information that the proxy reveals about the person using it. For example, transparent proxies add, to their HTTP requests, one of two HTTP headers - VIA or PROXY_CONNECTION - that are unique to proxies, and another HTTP header - X_FOWARDED_FOR - from which the original IP address can be determined. In contrast, Anonymous proxies, lack the X_FOWARDED_FOR header. High Anonymity proxies (also known as Elite proxies), unlike Anonymous proxies, can't be identified at all as proxies from their HTTP requests (ie. their requests don't include any of the three afore mentioned HTTP headers). A proxy which sends out HTTP requests from a different IP address than the ones it recevies them from is known as a Gateway proxy.
Proxy Types:
Open Proxies are called HTTP Elite, Anonymous and SOCKS 4 and SOCKS 5 Proxies. They can be used for Blackhat SEO Software or Scripts or to be anonymous (you need to setup the proxy in your browser)
Best sites for this type of proxy:
http://stealthproxy.org
http://xtremeproxies.com
Web Proxies: Great for surfing the Internet anonymously.
Best sites for this type of proxy:
http://anonymouslist.net
http://ninjaproxy.cc
"Private" Proxies: Proxies you buy peer IP, they get blocked very fast if you use them for Blackhat SEO.
Best sites for this type of proxy:
None recommended!
For more about buy proxies visit http://stealthproxy.org
