Information Architecture for the World Wide Web, Second Edition

Chapter 9. Thesauri, Controlled Vocabularies, and Metadata

A web site 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 to view the network of relationships between systems. In many large metadata-driven web sites, controlled vocabularies have become the glue that holds the systems together. A thesaurus on the back end can enable a more seamless and satisfying user experience on the front end.

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. As information architects we can draw upon these decades of experience, but we can’t copy indiscriminately. The web sites and intranets we design present new challenges and demand creative solutions.

But we’re getting ahead of ourselves. Let’s begin by defining some basic terms and concepts. Then we can work back toward the big picture.

Metadata

When it comes to definitions, metadata is a slippery fish. Describing it as “data about data” isn’t very helpful. The following excerpt from Dictionary.com ...