What is “Reverse Proxy” and “Load Balancing” in Nginx / Web server terms?

Question

These are two phrases I hear about very often, mainly associated with Nginx. Can someone give me a laymans defintion?

Answer 1

Here is the basic definition:

Reverse Proxy is a proxy host, that receives requests from a client, and sends it to one of the servers behind itself. Nginx and apache httpd are commonly used as reverse proxies. These are in the administrative network of the web server that a servers a request.

This is in contrast with a (forward) Proxy, which sits in front of a client, and sends requests on behalf of a client to a web server. As an example, your corporate network address translator is a forward proxy. These are in the administrative network of the client from where the request originates.

Load balancing is a function performed by reverse proxies. The client requests are received by a load balancer, and the load balancer tries to send that request to one of the nodes (hosts) in the server pool, in an attempt to balance the load across various nodes.