What is a REST API

A REST API is a fancy way of saying a REpresentational State Transfer. What that means is “hey server, tell me the current state of this thing I want from you”. State is what computer scientists call the current “state of mind” of the server, for example if you ask the server, “hey server give me a list of all the users” if will give you back a list of all the users at the exact moment you asked for them. As more users get added, then the next time you ask more users will be shown.

Not the easiest thing to understand but once you get it you will realise why it has become so popular over the years.

Here is a good representation of how a REST API works between a database and different users: