Main aspects of the Semantic Web

The Semantic Web is a vision of the Web where data has explicit meaning so that machines can process it. Its main aspects are:

1. Machine-understandable data and metadata: Content is described by metadata (data about data) in standard formats, so software can interpret what a page or resource means.
2. Unique identification with URIs: Every resource (person, place, concept) has a unique URI, so data from different sites can be linked without confusion.
3. XML (syntax): A common, structured syntax with user-defined tags and namespaces for the data.
4. RDF (data model): Describes resources by statements called triples (subject, predicate, object), e.g. (Ram, worksFor, TU). RDF Schema adds classes and properties.
5. Ontologies (OWL): Formal, shared vocabularies that define concepts and the relationships between them, allowing agreement on meaning (for example "Teacher is a kind of Person").
6. Logic, inference and rules: Reasoners deduce new facts from existing ones. Example: if "Ram is father of Hari" and "Hari is father of Shyam", then Ram is grandfather of Shyam.
7. Query (SPARQL): A query language to retrieve data from RDF stores.
8. Intelligent agents: Programs that use semantic data to do tasks for users, such as booking or comparison.
9. Proof and trust: Mechanisms (digital signatures, provenance) to verify the source and correctness of information.
10. Linked Data and interoperability: Connecting datasets (like DBpedia) into a global web of data.

Trust / Proof
Logic / Rules
Ontology (OWL, RDFS)
RDF (triples)
XML + Namespaces
URI / Unicode