3.2 Resources and Representations

The REST style characterizes communication between system components (where a component is, say, a web browser or a server) as a series of requests to which the responses are representations of resources.

A resource, in this context, is a “conceptual mapping” (Fielding). Resources themselves are not tied to a database, a model, or a controller.

What you actually do get hold of is never the resource itself, but a representation of it. This is where REST unfolds onto the myriad content types and actual deliverables that are the stuff of the web.