What are Taxonomies?

Taxonomies are ways to classify entries in a content type. A taxonomy is a single set of classifying information. Categories and tags are the two main taxonomies built into WordPress. A term is a single option within the taxonomy. For example, for Categories, each individual category is a term. "Categories" and "tags" are both, by design, very broadly-defined.  Your own taxonomies can be as specific as you need:

  • A Book content type could have a taxonomy called Genre with terms like Mystery, Romance, and Sci-Fi
  • A Vehicle content type could have a taxonomy called Brand with terms like Ford, Audi, and Jaguar
  • A Clothing content type could have a taxonomy called Size with terms like S, M, L, XL, and XXL

Whenever you need to categorize something by choosing from a set of possible values, chances are you should use a taxonomy. Let's say you're creating a content type called "Movie".  You're thinking about all the information you need to record for each movie, so you jot down:

  • Title
  • Synopsis
  • Release Date
  • Rating

Of that information, Title can be handled with the default title field.  Synopsis could be a text box field, and Release Date could be a date field.

Then you get to Rating.  At first, you think it could be a basic text field where you could type in the rating -- G, PG, PG-13 and so on.  But every movie you add is going to be one of five or six ratings.  It would make more sense to create a master list of those ratings, which you could then choose from whenever creating a movie.  You wouldn't have to worry about typos, and you could do cool things on your site like list movies by a specific rating.  That's a taxonomy.

Taxonomy terms can also have parent-child relationships, in the same way that post categories can have sub-categories. For example, we could have a taxonomy called Colors with terms Primary and Secondary. We could then add Red, Yellow, and Blue as child terms to the term Primary, and we could add Green, Orange, and Purple to the term Secondary.

Taxonomies are controlled via the “Taxonomies” item in the Creator menu of the dashboard.  Through there, you can reach screens that enable you to view all taxonomies, edit a taxonomy, or add a new taxonomy.