Differences in type specifiers

Question

What are the differences in following three resource type specifiers?

rdf:type
rdfs:Class
owl:Class

and when to use them?

Accepted Answer

In the first place, rdf:type is used as a predicate. One could for instance claim that Tim BL is a person:

<http://www.w3.org/People/Berners-Lee/card.rdf#i> rdf:type foaf:Person .

The latter two would be typically used as objects, to signify that something is a class (a group of resources with similar traits). In fact, simply stating that

A rdf:type B .

implies that B is a class (more specifically, an rdfs:Class):

B rdf:type rdfs:Class .

So we can infer from the first statement that foaf:Person is an rdfs:Class; this is also stated explicitly in the RDF version of the FOAF ontology.

owl:Class is a subclass of rdfs:Class. This has to do with restrictions on OWL Lite and DL reasoning, where some RDFS classes would not be 'proper' OWL classes. If you need OWL DL reasoning, you should use owl:Class.

Differences in type specifiers

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