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Semantic Web
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Semantic Web

The Semantic Web is a project that intends to create a universal medium for information exchange by giving meaning, in a manner understandable by machines, to the content of documents on the Web. Currently under the direction of its creator, Tim Berners-Lee of the World Wide Web Consortium, the Semantic Web extends the ability of the World Wide Web through the use of standards, markup languages and related processing tools.

Table of contents
1 Relationship to the World Wide Web
2 Components of the Semantic Web
3 See also
4 References
5 External links

Relationship to the World Wide Web

Currently, the World Wide Web is based primarily on documents written in HTML, a language that is useful for describing, with an emphasis on visual presentation, a body of structured text interspersed with multimedia objects such as images and interactive forms. HTML has limited ability to classify the blocks of text on a page, apart from the roles they play in a typical document's organization and in the desired visual layout.

For example, with HTML and a tool to render it (perhaps Web browser software, perhaps another user agent), one can create and present a page that lists items for sale. The HTML of this catalog page can make simple, document-level assertions such as "this document's title is 'Widget Superstore'". But there is no capability within the HTML itself to unambiguously assert that, say, item number X586172 is an Acme Gizmo with a retail price of €200, or that it is a consumer product. Rather, HTML can only say that the span of text "X586172" is something that should be positioned near "Acme Gizmo" and "€200", etc. There is no way to say "this is a catalog" or even to establish that "Acme Gizmo" is a kind of title or that "€200" is a price. There is also no way to express that these pieces of information are bound together in describing a discrete item, distinct from other items perhaps listed on the page.

The Semantic Web addresses this shortcoming, using the descriptive technologies RDF and OWL, and the data-centric, customizable markup language XML. These technologies are combined in order to provide descriptions that supplement or replace the content of Web documents. Thus, content may manifest as descriptive data stored in Web-accessible databases, or as markup within documents (particularly, in XHTML interspersed with XML, or, more often, purely in XML, with layout/rendering cues stored separately). The machine-readable descriptions allow content managers to add meaning to the content, thereby facilitating automated information gathering and research by computers.

Components of the Semantic Web

The Semantic Web is comprised of the standards and tools of XML, XML Schema, RDF, RDF Schema and OWL. The [OWL Web Ontology Language Overview http://www.w3.org/TR/owl-features/] describes the function and relationship of each of these components of the Semantic Web:

The usability and usefulness of the Web and its interconnected resources will be enhanced through:

The primary facilitators of this technology are URIs (which identify resources) along with XML and namespaces. These, together with a bit of logic, form RDF, which can be used to say anything about anything. As well as RDF, many other technologies such as Topic Maps and pre-web AI technologies are likely to contribute to the Semantic Web.

Another aspect of the Semantic Web is Friend-Of-A-Friend, FOAF, which allows you to describe yourself in terms of RDF.

See also


External links