‘‘The Semantic Web is not a separate Web but an extension of the current one, in
which information is given well-defined meaning, better enabling computers and
people to work in cooperation.’’
A definition for the Semantic Web begins with defining semantic. Semantic
simply means meaning.Meaning enables a more effective use of the underlying
data. Semantics give a keyword symbol useful meaning through the establishment
of relationships. The Semantic Web is simply a web of data described and linked in ways
to establish context or semantics that adhere to defined grammar and language
The Semantic Web defines a set of standardised technologies and tools in order to provide a solid foundation for making the web machine-readable. The Semantic Web infrastructure is based on several layers, each corresponding to a specific technology, and is commonly represented as stack. A visual representation of the Semantic Web stack.
URI-Unicode Unicode is the standardised character encoding used by computers. Unified Resource Identifier (URI) is the standard for identifying
XML extensible Markup Language (XML) is the standard syntax for structuring and describing many kind of data but does not carry any semantics
RDF Resource Description Framework (RDF).is the standardised metadata representation
RDF Schema RDFS, based on RDF, is a standardised and simple modelling language to describe resources and offers a basis for logical reasoning
SPARQL: SPARQL is the emerging standard for querying and accessing RDF stores
OWL– Ontology Web Language (OWL), a more advanced assertional language, enables more complex resource descriptions and logical reasoning.OWL adds more vocabulary for describing properties and classes: among others, relations between classes (e.g. disjointness), cardinality (e.g. “exactly one”), equality, richer typing of properties, characteristics of properties (e.g. symmetry), and enumerated classes.
Rule-SWRL: Semantic Web Rule Language (SWRL) based on a combination of the OWL DL and OWL Lite sublanguages.The proposal extends the set of OWL axioms to include Horn-like rules. It thus enables Horn-like rules to be combined with an OWL knowledge base. Atoms in these rules can be of the form C(x), P(x,y), sameAs(x,y) or differentFrom(x,y), where C is an OWL description, P is an OWL property, and x,y are either variables, OWL individuals or OWL data values
Logic A reasoning system that infers new knowledge from ontologies and checks data consistency
Proof The “Proof” layer gives a proof of the logical reasoning conclusion by tracing the deduction of the inference engine.
further Information to SemanticWeb Org