RESTful APIs can simply be defined as a set of rules used to build web services where you retrieve or manipulate resources. A resource is typically a kind of document—it could be an HTML document (such as a web page), a JSON document (for pure information sharing), or some other type of document. JSON stands for JavaScript Object Notation; this is because it basically refers to how you would write the object in JavaScript. It's very popular and is widely used. 

For the majority of RESTful APIs, HTTP is utilized as the communication layer for the API:

The topic can be very lengthy; however, there are a few simple facts and concepts ...

Get Hands-On Full Stack Development with Go now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.