I was not able to attend the several workshops on “taxonomy” at the recent WebContent2010 conference (#wcconf) in Chicago: Tough choices were made. Yet I think I got a lot out of those workshops because of the seriously faithful tweeting coming out of them, and when I said so to some new friends, they almost all said, “How? I didn’t understand any of it…overwhelming.” I replied that when you follow a tweetstream, you only see what people understand, already interpreted for you. (Which is a recommendation, really, to follow conferences you can’t attend: Done well, the tweets will give you at least the essential points.)

Amid the summary tweets of the workshops’ content, however, I saw comments such as these:

“A workshop and a session on taxonomy and I’m still confused. Is it just me? #wcconf” – @EvanKittleton

“Ouch. My head hurts. Taxonomy not an easy beast to wrestle. #wcconf” –  @cc_holland

A lot of the confusion centered on how the idea of taxonomy relates to—and differs from—other elements of Information Architecture, such as sitemaps and navigation. Are they the same thing? Is it just your metadata?

With the guidance of my best-bud colleague Becky Bristol as technical reviewer (@paintingblue) I’m going to try to “disambiguate” it, that is, to explain and clarify.

Disclaimer: I’m an explainer, not a taxonomist, so if you’d like to help with the definition, please by all means chime in.

The Roots of Taxonomy

“Taxonomy” is an ancient scientific practice. It means to find names for things. In naming things, you try to figure out how sets of things are related to one another, so that each, unique item will not only have a unique name, but also a reference to the others to which it relates.

Taxonomy creates a hierarchy of inheritance, from general down to specific and back: A giant tree, on which there is a unique place for every item, like the leaves at the ends of twigs at the ends of branches connected to a trunk and running deep into the earth.

In order to build a taxonomy in the scientific sense, you have to create a framework that tells you how to name a thing. This is the “schema.” The most famous schema was created by Carl Linnaeus, an 18^th Century Swedish botanist, to categorize and name life on Earth. It has eight, major taxonomic ranks:

Domain -> Kingdom -> Phylum (botany)/Division (zoology) -> Class -> Order -> Family -> Genus -> Species

If you’re REALLY geeky, you can lay it out in Latin:

Regio -> Regnum -> Phylum/Divisio -> Classis -> Ordo -> Familia -> Genus -> Species

There are only certain terms you can put into those fields. Imagine drop-down boxes from which you MUST choose. Let’s try it on ourselves, humans:

When the terms don’t apply at a certain point, then you get to pick a new term, which at that point, creates a new branch. If you find a new item in nature, something that hasn’t been named before, you get to name it yourself, but you will use the same set of terms down the tree as far as you can to demonstrate your new species’s relationship to all other life.

Taken altogether, this classification system becomes the official way of understanding the whole world of animals, plants, and bacteria. Taxonomy is powerful because it is universally adopted: You could try to work out a new system, but then you’d have to explain it to everyone and get buy-in for it to mean anything to anyone else but you. It is at this point that we make the transition to the Web…

Taxonomy on the Web

Now at some point, the word “taxonomy” was appropriated by information architects to talk about web content. When one discipline borrows from another’s, the meaning and use of the term can change significantly, and so “taxonomy” doesn’t mean to the web professional quite what it means to the biologist.

A website’s taxonomy describes how all the content relates to each other. Through its rigidly controlled network of meaning, there is a way to say with confidence:

“Item X and Item Y are in the same group. When you look at Item X, you may also be interested in Item Y.”

We take this kind of connection for granted these days because Amazon and other e-commerce giants have made such ubiquitous and successful use of taxonomy to sell related things, but it’s really quite difficult to establish those kinds of relationships in your content without taxonomy.

In summary to this point, then, “taxonomy” on a website is a classification system that maps all your content to other content. Taxonomy on a website creates a scaffold that holds your content together.

Not one taxonomy, but many

It gets a little more complicated from here. Whereas in a biological taxonomy, we’re dealing with only one dimension of relationship, the ultimate relationship of one species to another through its name, on a website, there can be many classification systems to govern the relationship of content along many dimensions.

Let’s take with a clothing retailer. The most basic taxonomy would divide the products into groups of “kind” to answer the question, “What article of clothing is this?”

Clothing for the upper body

• Shirts
  • Blouses
  • T-shirts
  • Polos
  • Turtlenecks
• Jackets
  • Blazer
  • Windbreaker
• Sweaters
  • Cardigan
  • Pull-over
  • Vest

Clothing for the legs

• Pants
  • Dress pants
  • Jeans
  • Shorts
• Skirts
  • Full-length
  • Wraps
  • Culottes (really a hybrid)

Accessories

• Jewelry
  • Rings
  • Earrings
  • Watches
  • Necklaces
• Belts
• Hats
• Bags

So far, so good. We have a system for identifying items by basic type. But that’s not so good for sales.

There will be, then, additional taxonomies to build up a multidimensional system that organizes products into classes: For women or men, girls or boys; for casual, work or formal contexts; for outdoor or indoor; by color; by season; by ethnic origin; and so on, and so on…

But that’s just the products. There will be other content that accompanies these products, and all that content must also be organized into categories.

• “How to” content might include tieing neckties, caring for leather, assembling an ensemble for an evening out in Paris.
• “About us” content might go through all the ways that this company works for environmental activism.
• Product information might include stories about where the materials came from, or who made them.

The taxonomy must account for all these dimensions of content description and classification, so that when you pull up the product page for that pair of shoes you’re considering, you also can see:

• What other colors are available?
• What other shoes are in its class?
• How do you care for them?
• What accessories would complete your outfit?
• How have other customers worn this item? (From their photos)
• How long it would take to get them if you clicked the button right now…?

Taxonomy implemented through metadata

All this work of understanding the interrelationship of content has a specific and practical end: Metadata.

It is beyond the scope of this article to explain the process of developing taxonomic systems and how they are then translated into metdata for your web content. It is crucial, however, to recognize that having a clear, controlled system of metadata, which is then meticulously and consistently connected to your content, is the only way to ensure that your search and coordinated applications serve up the content the user expects, in the language the user expects, in combinations that make sense to the user.

Rich, interactive experiences require taxonomy

Creating rich internet applications (RIAs) is partly about the technology to evaluate and serve up all these connections, but it is impossible without care, design, and maintenance of your content’s taxonomy.

Again, unlike our scientific counterparts, there can be no, single, universal taxonomy for web content because each content domain has its own context of purpose, vocabulary, and peculiarity.  There are commercially available taxonomic systems to get you started, but they all have to be evaluated for your specific purpose, and there will always be adaptation of the metadata.

Taxonomy, Navigation, and Sitemaps

A lot of the confusion in the workshops dealt with how a website’s taxonomy relates to the other aspects of its information architecture. As we explore these concepts, keep in mind that when done well, the taxonomy is completely invisible to the user. It just makes everything run smoothly.

Sitemaps

The sitemap reveals the website’s overall organization. Every bit of content on a website needs a primary “home.” Ultimately, when you reach a content item, you are (virtually, of course) in a particular location on the site. The information architect’s job is to choose from the infinite range of organizational possibilities to anchor the user experience, which then is the foundation for the richness that the taxonomy creates.

The sitemap probably will reflect some basic aspects of the taxonomy underlying the content, but when you consider the richness and complexity described above, any relation between the sitemap and the taxonomy will be loose.

Navigation

Navigation is more closely related to the sitemap than to the taxonomy. The main navigation provides the user an organized path around the website, intended for browsing. Like the sitemap, it may reflect some aspects of the taxonomy, but it doesn’t have to.

The taxonomy will enable, however, the local navigation options through access points to content elsewhere on the site, reached through the relatedness of content.

IAs help you put it together!

It’s the job of information architects to work all these intricacies out. The skills for designing the taxonomy and associated metadata are extensive and precise. The content strategist helps to define the content domain and the language that will best represent it, but the IA will be able to build an organizational framework that links the content domain with the technical wizardry that serves up the user experience.

In conclusion, as my best-bud Becky says, “There is no right or wrong way of [creating taxonomy]. The trick is to come up with a taxonomy that works for your users.”

I hope that this article has helped to clarify the definition of taxonomy and its application. Please offer corrections, amplifications, and clarification. It’s a matter to wide importance, and we need to get it right!