Scientific American: The Semantic Web

-- A new form of Web content that is meaningful to computers will unleash a revolution of new possibilities

Extracts from the article: -- The challenge of the Semantic Web, therefore, is to provide a language that expresses both data and rules for reasoning about the data and that allows rules from any existing knowledge-representation system to be exported onto the Web.-- Two important technologies for developing the Semantic Web are already in place: eXtensible Markup Language (XML) and the Resource Description Framework (RDF). --- XML = create your own language, RDF = encode meaning, triples made of (subject, verb and object of an elementary sentence) --- Subject, objects and verbs are URI --- because two databases may use different identifiers for what is in fact the same concept, such as zip code.--- A solution to this problem is provided by the third basic component of the Semantic Web, collections of information called ontologies.--- ontology is a document or file that formally defines the relations among terms ---The most typical kind of ontology for the Web has a taxonomy and a set of inference rules. --- The taxonomy defines classes of objects and relations among them. For example, an address may be defined as a type of location, and city codes may be defined to apply only to locations, and so on --- An example of a page marked up for such use is online at http://www.cs.umd.edu/~hendler. If you send your Web browser to that page, you will see the normal Web page entitled "Dr. James A. Hendler." As a human, you can readily find the link to a short biographical note and read there that Hendler received his Ph.D. from Brown University. A computer program trying to find such information, however, would have to be very complex to guess that this information might be in a biography and to understand the English language used there.--- Human endeavor is caught in an eternal tension between the effectiveness of small groups acting independently and the need to mesh with the wider community.---