There are also up, down, charmed, and strange proxies, with obvious applications in quantum computing, nonrepudiation, and dairy farming. Strange proxies were thought to be purely theoretical until an accident involving a rubber band, a liquid lunch, and a particle accelerator collided a transparent squid with varnish at relativistic velocities and the resulting core dump subsequently examined for overflows.

I think preprending “forward” was meant to avoid confusion. Reverse proxy and Forward proxy, but now you’re wondering if there’s 3 types of proxies.

I think people add 'forward' because reverse proxies are now a lot more common than traditional proxies, so people will assume reverse proxy if you just say 'proxy'.

I also landed on similar pages and now I am confused about SOCK5 proxy vs HTTP proxy vs SSL proxy as outlines in the links above.

A reverse proxy waits for a request from another server and responds to the calling server. You can think of a reverse proxy as the "deep backend" in a web stack.

One of the first and most powerful reverse proxies was mod_perl running under httpd. Typically 5 or 6 mod_perl instances can handle requests from 300 normal httpd children.

So when somebody says "forward proxy" they usually mean "not a reverse proxy."

Mod_perl doesn't feel like a reverse proxy to me, it's just executing Perl in the Apache process directly. Fastcgi, on the other hand, is passing requests to persistently running standalone Perl instances, over a pipe, Unix domain socket, or tcp connection. Which feels more like a reverse proxy.

Mod_perl would more accurately be called a “commonly reverse proxied app server.” Typical setup was to have another Apache instance in front of it handling static requests and reverse proxying app requests.