Graph depicting relationship of URI to resource to representation.

When speaking on the design of the Web, it is imperative to establish a solid conceptual model of the relationship between URIs, resources and their representations.

The basic unit of the Web is the resource. A resource is an abstract message of finite length. A resource can have many literal representations that convey its meaning in different ways. It is these representations that are commonly understood to frequently originate as the contents of files. A resource is referred to by one or more identifiers — a synonym for names. These identifiers, generically called URIs — or URLs in the case of HTTP, contain their own shapes and meanings.

This section is therefore further subdivided into the following parts: