On Martin Fowler’s site “Richardson Maturity Model: steps toward the glory of REST”
Introduces REST through a series of steps/levels that you might even go through while implementing and exposing webservices for your application.
This is how I read the 4 levels translate:
Level 0: Using something like SOAP and a single end-point (URI)
Level 1: Introducing multiple URIs (each acting like an end-point), to perform different operations.
Level 2: Using the HTTP verbs (Get,Post,Put,Delete, etc…) when performing different types of operations on each URI that you expose.
Level 3: Adding links in your responses to operation requests that allow for discoverability of what can be done next.