When people search for proxies online, they often stumble around looking for the safest and most secure ones available, but head for the free ones. Unfortunately the free ones are rarely very secure, or fast and certainly you couldn't call them ninja proxies. However hopefully these definitions will help you search out some options.
The three main types are transparent, anonymous and elite proxies but these definitions are open to interpretation, The most accepted definitions though are explained in the video. Remember though, just because someone calls a ninja proxy - an anonymous or elite proxy doesn't mean it is.
The video also demonstrates a quick way of checking how secure and private a proxy server actually is.