Ontologies and the semantic web

How ontologies provide the semantics, as explained here with the help of Harry Potter and his owl Hedwig. While phenomenally successful in terms of amount of accessible content and number of users, today’s Web is a relatively simple artifact. Web content consists mainly of distributed hypertext and hypermedia, accessible via keyword-based search and link navigation. Simplicity is one of the Web’s great strengths and an important factor in its popularity and growth; even naive users quickly learn to use it and even create their own content. However, the explosion in both the range and quantity of Web content also highlights serious shortcomings in the hypertext paradigm. The required content becomes increasingly difficult to locate via search and browse; for example, finding information about people with common names (or famous namesakes) can be frustrating. Answering more complex queries, along with more general information retrieval, integration, sharing, and processing, can be difficult or even impossible; for example, retrieving a list of the names of E.U. heads of state is apparently beyond the capabilities of all existing Web query engines, in spite of the fact that the relevant information is readily available on the Web. Such a task typically requires the integration of information from multiple sources; for example, a list of E.U. member states can be found at europa.eu, and a list of heads of state by country can be found at rulers.org.