To identify web identifiers(URIs) uses RDF.
Also using RDF we can describe resources with properties and their respected values.
Resource: resouces is anything that have a URI.Like: "http://www.r4r.co.in/RDF"
Property: It is a resource than can have name like: "author" or "homepage".
Property value: It is used to define the value of property. Like: "Vivek Kr. Agarwal" or "http://www.r4r.co.in"
Example: I define you RDF by using an example.
<author>Vivek Kr. Agarwal</author>