Magazine article Online

The Semantic Web: Differentiating between Taxonomies and Ontologies

Magazine article Online

The Semantic Web: Differentiating between Taxonomies and Ontologies

Article excerpt

There's a new vision of the Web--the Semantic Web--that will dramatically improve Web-based services and products. It creates a setting where software agents perform everyday jobs for end-users. Deploying hierarchies, metadata, and structured vocabularies, the Semantic Web expands basic Internet functions. According to Tim Berners-Lee (writing with James Hendler and Ora Lassila in the May 7, 2001 issue of Scientific American) and the World Wide Web Consortium (W3C), the Internet has the potential to act as a treasured valet or lady's maid [], an all-knowing, trustworthy source of practical information.

The Semantic Web is about making people's life easier by answering a whole host of familiar ready-reference queries. Berners-Lee imagines a natural language interface for the Semantic Web. For example, a user could type, "What is the best graduate program in business in the New York City area?" An intelligent agent would scurry out onto the Web, compare university rankings such as The U.S. News and World Report or the BusinessWeek Guide to the Best Business Schools, and return a list of names. The intelligent agent would then fetch the university applications and assorted financial aid information for the top five graduate programs.

Some of the traditional skills of librarianship--thesaurus construction, metadata design, and information organization--dovetail with this next stage of Web development. Librarians have the skills that computer scientists, entrepreneurs, and others are looking for when trying to envision the Semantic Web. However, fruitful exchange between these various communities depends on communication.

Commonalities exist--as do differences--between librarians who create taxonomies and computer scientists who build ontologies. Mapping concepts, skills, and jargon between computer scientists and librarians encourages collaboration. Speaking the language of other disciplines and professions helps librarians remain a vital part of the Web development community.


The Semantic Web entails adding an extra layer of infrastructure to the current HTML Web. Metadata and structured vocabularies make it easier for databases to communicate with each other. A major problem with the Internet today is data fragmentation. With the Semantic Web, computers understand the meaning of a Web page by following hypertext links from Web documents to topic-specific ontologies. For instance, ontologies offer cross-references so a computer understands that "movie," "film," "flick," and "motion picture" are different expressions of the same concept.

While intelligent agents do the visible labor of the Semantic Web, taxonomies will be facilitating communication among machines behind the scenes. For computers flung around the world to work together, a common set of terms-vocabularies--is needed and then rules that lay out how those terms work together. Taxonomies are an important part of what makes the Semantic Web "intelligent." Vocabularies and the relationships that exist between selected terms help machines to understand conceptual relationships as humans do.

Computer scientists--along with librarians--are working to solve problems of information retrieval and the exchange of knowledge between user groups. Ontologies or taxonomies are important to a number of computer scientists by facilitating the sharing and reuse of digital information. According to Tom Gruber, an artificial intelligence scholar at Stanford University, the ultimate goal for computer scientists is agreeing upon an authorized set of ontologies that can be reused and applied across multiple disciplines [].


Ontologies and taxonomies are, in functional terms, often used as synonyms. Computer scientists call hierarchies of structured vocabularies "ontologies" and librarians deploy the term "taxonomy. …

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