What is a Proxy Server?

A proxy is a piece of software or hardware that sits between a client and a server to facilitate the traffic flowing between them.

Nothing about that sentence says which side it stands next to, and that turns out to be the whole story. Stand it next to the clients and you get a forward proxy. Stand it next to the servers and you get a reverse proxy. They are built from the same idea and used for opposite reasons.

Forward Proxy

A forward proxy is a server that sits in front of one or more client machines and acts as an intermediary between those clients and the internet