Transparent Proxy
This proxy does not hide information about your IP address:
REMOTE_ADDR = proxy IP
HTTP_VIA = proxy IP
HTTP_X_FORWARDED_FOR = Your IP
The function of the proxy server is not to increase your anonymity on the Internet. Its purpose is to monetize information, organize shared access to the Internet from several computers, etc.
Anonymous Proxies
All proxy servers, which hide the IP address of the client in any way are called anonymous proxies.
Simple Anonymous Proxy
This proxy server does not hide the fact that a proxy is used, but replaces your IP with its own:
REMOTE_ADDR = proxy IP
HTTP_VIA = proxy IP
HTTP_X_FORWARDED_FOR = proxy IP
This proxy is the most widely used among other anonymous proxy servers.
Distorting Proxies
As with any simple anonymous proxy server, it does not hide the fact that a proxy server is used. However, the client’s IP address (your IP address) is replaced with another IP (arbitrary, random):
REMOTE_ADDR = proxy IP
HTTP_VIA = proxy IP
HTTP_X_FORWARDED_FOR = random IP address
High Anonymity Proxies
These proxy servers are also called “high anonymity proxies”. Unlike other types of anonymous proxy servers, these proxy servers hide the fact of proxy usage:
REMOTE_ADDR = proxy IP
HTTP_VIA = not specified
HTTP_X_FORWARDED_FOR = not specified
That means that the value of the variable is the same as if the proxy is not used, except for one very important thing. A proxy IP is used instead of your IP address.
Summary
Depending on the purpose, some proxies are transparent and anonymous. However, remember, by using a proxy server you only hide your IP from the web server, but other information (about browser configuration) can be accessed!