web services - Can you explain the Web concept of RESTful?

Question

Looking for clear and concise explanations of this concept.

Answer 1

A RESTful application is an application that exposes its state and functionality as a set of resources that the clients can manipulate and conforms to a certain set of principles:

• All resources are uniquely addressable, usually through URIs; other addressing can also be used, though.
• All resources can be manipulated through a constrained set of well-known actions, usually CRUD (create, read, update, delete), represented most often through the HTTP's POST, GET, PUT and DELETE; it can be a different set or a subset though - for example, some implementations limit that set to read and modify only (GET and PUT) for example
• The data for all resources is transferred through any of a constrained number of well-known representations, usually HTML, XML or JSON;
• The communication between the client and the application is performed over a stateless protocol that allows for multiple layered intermediaries that can reroute and cache the requests and response packets transparently for the client and the application.

The Wikipedia article pointed by Tim Scott gives more details about the origin of REST, detailed principles, examples and so on.