RDF Rules

RDF uses Web identifiers (URIs) to identify resources.

RDF uses properties and property values to describe resources.

RDF resources, properties, and property values

RDF uses Web identifiers to identify things and describes resources through properties and property values.

Explanation of resource, property, and property value:

  • ResourceIs anything that can have a URI, such as "http://www.codew3c.com/rdf"
  • PropertiesIs a resource with a name, such as "author" or "homepage"
  • Attribute ValueIs the value of some attribute, such as "David" or "http://www.codew3c.com" (note that an attribute value can be another resource)

The following RDF document can describe the resource "http://www.codew3c.com/rdf":

<?xml version="1.0"?>
<RDF>
  <Description about="http://www.codew3c.com/RDF">
    <author>David</author>
    <homepage>http://www.codew3c.com</homepage>
  </Description>
</RDF>

Tip:The above is a simplified example. The namespace is ignored.

RDF Statement

The combination of a resource, attribute, and attribute value can form aStatement(also known as the statement'sObject,PredicateAndSubject)

Please see some specific examples of statements to deepen your understanding:

Statement: "The author of http://www.codew3c.com/rdf is David."

  • The subject of the statement is: http://www.codew3c.com/rdf
  • The predicate is: author
  • The subject is: David

Statement: "The homepage of http://www.codew3c.com/rdf is http://www.codew3c.com".

  • The subject of the statement is: http://www.codew3c.com/rdf
  • The predicate is: homepage
  • The subject is: http://www.codew3c.com