Chapter 10. Thesauri, Controlled Vocabularies, and Metadata

The basic tool for the manipulation of reality is the manipulation of words.

Philip K. Dick

In this chapter, we’ll cover:

  • Definitions of metadata and controlled vocabularies

  • An overview of synonym rings, authority files, classification schemes, and thesauri

  • Hierarchical, equivalence, and associative relationships

  • Faceted classification and guided navigation

An interactive information environment—like a website—is a collection of interconnected systems with complex dependencies. A single link on a page can simultaneously be part of the site’s structure, organization, labeling, navigation, and searching systems. It’s useful to study these systems independently, but it’s also crucial to consider how they interact. Reductionism will not tell us the whole truth.

Metadata and controlled vocabularies present a fascinating lens through which we can view the network of relationships between systems. In many large metadata-driven products, controlled vocabularies have become the glue that holds the systems together. A thesaurus on the backend can enable a more seamless and satisfying user experience on the frontend.

In addition, the practice of thesaurus design can help bridge the gap between past and present. The first thesauri were developed for libraries, museums, and government agencies long before the invention of the World Wide Web. We can draw upon these decades of experience, but we can’t copy indiscriminately. ...

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