Generally, there are two types of proxy servers available which are Forward Proxy and Reverse Proxy
Let us Discuss the Differences between the Forward Proxy and Reverse proxy. Forward Proxy is used by the client as a Web Server and Reverse Proxy is used by the Server as a Web Server. Forward proxy can sit in the same internal network as the client or it can be on the Internet.
Forward Proxy is used at a client-side in order to bypass the firewall preventions to visit the blocked Websites. Using Forward Proxy, you can hide your real IP Address so the website can be able to access though it is blocked with IP Range. Recipient Web Server may detect Forward Proxy and Block the request as well. There are several Proxy services online which can use Forward proxy and can change your IP address at every new web page in order to access the Blocked Website.
Forward Proxy Server can be useful as a Cache Server. If any file is downloaded multiple times, it can save it as a cache so at a time of Download it can download the data directly from the caching. Such Proxy server always sits at the Internal Network. It can be web proxy, HTTP proxy, SOCKS proxy, etc
Reverse Proxy also sits at the Internal network in order to get High Availability and Load Balancing for your website. Your Website may reside behind a Reverse proxy with several Web Servers. Reverse Proxy gets the incoming request from the Internet and forwards it to your Webservers. Since Reverse Proxy used in Backend, your website visitor may not get an idea about it. Nginx can work as a WebServer as well as Reverse Proxy. Alternatively, you can use HAProxy which is an Open source Reverse Proxy server. One can control the Incoming traffic using Reverse Proxy and distribute the request to internal web servers.