The Semantic Web is an idea for extending the World Wide Web so that information is published not only for people to read but in a structured form that software can interpret and link. Tim Berners-Lee, the web's inventor, set it out in a 2001 article. The World Wide Web Consortium (W3C) developed standards to make it work, including RDF for describing data as simple statements, OWL for defining vocabularies and relationships, and SPARQL for querying linked data. The full vision of software agents reasoning across the web has not arrived, but the ideas live on in knowledge graphs used by search engines, in schema markup on web pages and in data standards used by governments and finance. The Semantic Web was sometimes called "Web 3.0", which causes confusion with blockchain-based Web3, a separate idea focused on ownership rather than meaning. Also see decentralised identifier and interoperability.
Last updated 13 Nov 2026