RDF schema is actually an semantic extension of RDF. Semantic here means focussing on the relation between phrases, properties, classes. RDF schema provides a mechanism that describe groups of related resources and relationship between resources. RDF describe resources with classes, properties and values. The RDF schema language is used for declaring classes and its type. Classes in RDF schema are much like classes in object oriented programming language. RDF schema provide a framework to describe classes and properties.
Classs: Resources are divided into groups which are known as classes. Classes represent the concept of subjects, objects and predicates, etc. All data types are classes such as rdfs:Class, rdfs:Literal etc.
Properties: Properties are the instances of class which describes a relation between subject and object resources. Such as rdf:predicate, rdf:subPropertyOf.
<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.indo.org/rdf-syntax-ns#" xmlns:rdfs="http://www.indo.org/rdf-schema#" xml:base="http://www.fruit.fake/fruits#"> <rdf:Description rdf:ID="fruits"> <rdf:type rdf:resource="http://www.indo.org/rdf-schema#Class"/> </rdf:Description> <rdf:Description rdf:ID="mango"> <rdf:type rdf:resource="http://www.indo.org/rdf-schema#Class"/> <rdfs:subClassOf rdf:resource="#fruit"/> </rdf:Description> </rdf:RDF>
Classes and Properties must be define in using RDF Schema.