Toggle Menu

1.5 What exactly is a REST API?

REST: Everyone has heard about it, but not everyone has the same definition. It’s become synonymous with the idea of a “web API,” but it’s real meaning is quite a bit more specific.

In short it’s a web API that is designed to work like the WWW.


  • API terms
    • REST
    • HTTP Methods (Verbs)
    • HTTP Status Codes
    • Media Type


Set of guidelines that define best practices for making an API. REST is not a formal specification, but rather a set of principles that guide API design, making your API work like the World Wide Web.

From wikipedia Representational state transfer, an architectural style consisting of guidelines for creating scaleable web services.

If an API is following the REST principles it should have the following aspects:

  1. base URI, such as
  2. an Internet media type for the data. This is often JSON but can be any other valid Internet media type (e.g. XML, Atom, microformats, images, etc.)
  3. Use standard HTTP methods (e.g., GET, PUT, POST, or DELETE)
  4. hypertext links to reference state
  5. hypertext links to reference related resources

The Academic Roots of REST API Guidelines

HTTP Methods

Define the desired action to be used when accessing a resource. You are likely familiar with GET and POST, but there are also: HEAD, OPTIONS, PUT, DELETE, TRACE and CONNECT.

Safe and UnSafe Methods.

Safe methods are, by convention: GET, HEAD, OPTIONS and TRACE. Accessing with these methods will not change the state of the application.

By contrast, methods such as POST, PUT, DELETE and PATCH are intended for actions that may cause side effects either on the server.

more info

Media Type

The Internet media type identifies the type of data the file contains. HTML pages will have the media type text/HTML and most of the APIs you use will be application/json. Some might use application/xml - I’m sorry.