Like the World Wide Web, the Semantic Web is decentralized -- no one organization or agency has control over all of its rules and content. However, some people and organizations have taken leadership roles in the development of Semantic Web guidelines and protocols. These include the World Wide Web Consortium (W3C), its director Tim Berners-Lee and its member organizations. The W3C is not a research organization, so universities, other organizations and the public also play an active role in Semantic Web development.
Some areas of the World Wide Web have already incorporated Semantic Web components. These include RSS feeds, which use RDF, and the Friend-of-a-Friend (FOAF) project, which proposes to create machine-readable personal web pages.
But much of the Semantic Web's function and practicality are still in development, and there are some pretty big obstacles to overcome. Decentralization gives developers the freedom to create precisely the tags and ontologies that they need. But, it also means that different developers might use different tags to describe the same thing, which could make machine comparisons difficult. Critics also question the "identity problem" -- does a URI represent a Web page, or does it represent the concept or object the page describes. For example, is "http://www.starwars.com" meant to represent the "Star Wars" films, or just the Web page?
Some developers disagree on whether the Semantic Web should rely more heavily on rules or on ontologies. Critics also say that the project is enormously impractical. First, people don't actually think in terms of the graphs that RDF uses. Second, it seems unlikely that businesses and existing sites will actually devote the time and resources it would take to add all the necessary metadata. In the future, off-the-shelf software might include options for adding metadata when creating new documents, but that tool still might not make the project feasible on a larger scale.
For lots more information on the World Wide Web and the Semantic Web, check out the links on the next page.