What are Rest Architectural Elements?

Rest Architectural style defines parts of Restful service as key conceptual elements. For e.g. while we make a Rest request to a Server, the information returned by the Server is called a Resource. Let us take a quick look at the key conceptual elements in a RESTful Web Service. Its elements are:

Resource: Information stored on a Server, which can be requested by a client. It could be Weather info or may be employee details
Resource Identifier: Now that we have a resource defined, we need to uniquely identify the resource. That is actually the complete URL/
Representation: A resource is the actual data. Now this data can be represented as an XML, HTML or may be simple text. That is what is called a Representation.
Representation Metadata: In order for the Clients to specify and process a resources given in a particular Representation (XML or HTML etc) some extra data (Metadata) needs to be passed in the request.