A taxonomy defines the way different items relate to each other, and it makes connections between content based on a built-in understanding of these relationships. Sounds pretty high-tech, right? It is - but it's not anything new, either.

Taxonomy is a kind of buzz word - what we're really talking about is a faceted classification system. The idea of faceted classification was invented by a S. R. Ranganathan he's the Einstein of library science.

Until faceted classification, most organization was based on hierarchies. Take an art object – Van Gogh’s Starry Night painting. In a hierarchy, you might find it under Painting > Post-Impressionism > Van Gogh > Starry Night. If you don’t know that Van Gogh is considered a post-impressionist, you’re out of luck. Okay, so let’s try a different hierarchy. How about Painting > Dutch > Van Gogh > Starry Night? But what if you didn’t know that he’s Dutch? You see the problem.

With faceted classification, you can describe a subject in terms of its attributes. These attributes are organized into groups called facets. Even if a user doesn’t know all the attributes, they can still find what they’re looking for. For example, here are a few rough facets we could use to describe art:

Style (Impressionist, Post-Impressionist, Modern, etc.)
Country (Holland, France, China, etc.)
Media (Oil, Watercolor, Charcoal, etc.)
Time period (20th century, 19th century, etc.)
Subject Matter (Still life, landscape, portrait, etc.)

We can then combine these attributes to describe a particular item. Starry Night is a 19th century landscape, painted in oil by a Dutch artist in the Post-Impressionist style – the order doesn’t matter, and you can still find the painting even if you don’t know every attribute. This system also educates its users – when I get to the Starry Night, I learn that Van Gogh is a Dutch post-impressionist.

In a faceted classification, information has context, and since the system understands that context, it really lets you explore. If you’re looking at a page about Starry Night, you can use the facets to get to any related works of art. Change the period and style, and you’ve got Vermeer’s View of Delft – in a hierarchy, you’d have to start all over again, but with a faceted system, it’s right there.

Developing this type of taxonomy is challenging, but it’s worth it. It’s easy to update and maintain, and best of all, it lets your visitors spend their time learning and exploring, not trying to figure out if political science is buried under humanities or social sciences.