Last time on “WordPress & Taxonomies”…
Part 1 introduced the words “Taxonomy” and “Terms.” With that in mind, Part 2 covered the two default taxonomies in WordPress, “Categories” and “Tags.” But what if those aren’t enough? This post will outline the steps you’ll need to take to implement custom taxonomies on your own site in WordPress.
So now that you are starting to understand Categories and Tags, brace yourself, there’s more! WordPress can also make use of additional taxonomies with the “Custom Taxonomies” feature. A Custom Taxonomy can be hierarchical—like Categories—or non-hierarchical—like Tags.
For example:
- A computer blog might set up a “Brand” taxonomy for terms like “Apple,” “Dell,” “HP,” and “Lenovo.”
- An interior design blog might use a “Colors” taxonomy with the terms including “red,” “blue,” and “green.”
- A classroom blog might employ a “Subject” taxonomy for “Social Studies,” “Math,” “Science,” “Language Arts,” and “Electives.”
Custom Taxonomies are primarily useful in two situations:
- You have a specific set of terms that all make sense together rather than dumping them in the catch-all “Tags” taxonomy. In the Mark’s Meals example, Ingredients is a perfect use-case for a stand-alone taxonomy.
- You have a specific type of custom post in WordPress that needs a taxonomy of its own. One common setup I use with clients is a People type of content that has a “Role” taxonomy to sort whether a person is a “Board Member,” “Staff,” or “Volunteer.”
Putting These To Use
So if you want a custom taxonomy, you’ll need either a plugin or code snippet depending on your technical comfort level with web development.
There are quite a few plugins to add Custom Taxonomies, but the one I’ve used the most is Custom Post Type UI (or CPT UI).
If you want to do it with code, you’ll use the register_taxonomy() function. While most tutorials recommend putting that code in the functions.php file of the theme, I strongly recommend making a small “mu-plugin.” Doing this means that the taxonomy and its terms won’t disappear if you change your theme.
Detailed instructions on all the different variations of Custom Taxonomies in WordPress is beyond the scope of this article, but hopefully the plugin recommendation or function is enough to get you started. Head to Google with either and you’ll find tutorials aplenty.
Doing More
Once you have the taxonomy setup, you’ll use it just like Categories or Tags. The interface for selecting your terms will match the Categories interface if the taxonomy is “hierarchical” and match the Tags interface if it isn’t.
Some WordPress features will automatically detect the taxonomy and let you use it to make new tag clouds with the Tag Cloud widget or put it in menus. ((To add a custom taxonomy term to a menu, you’ll probably have to go to “Screen Options” on the Menus page and check the box next to the taxonomy name. Then you’re ready to add Custom Taxonomy terms to your menu!))
For other features, you’ll need plugins to help you get the most out of your new taxonomy and terms. Here are a few I’ve used successfully in the past:
- TC Custom Taxonomy Filter – Lets you filter posts in the admin so you see only posts in a specific term. Handy for content-heavy sites that use Custom Taxonomies. I’m even a contributor to this plugin!
- Taxonomy List Shortcode – Allows you to output a list of posts with a specific term anywhere in a WordPress post.
- Better Tag Cloud – Gives you greater control over the appearance of tag clouds and includes Custom Taxonomy support.
- List Custom Taxonomy Widget – Similar to the “Categories” widget but with support for Custom Taxonomies.
Wrapping Up: Taxonomies, Terms, Categories, Tags, and Custom Taxonomies (Phew!)
You made it! Custom Taxonomies, Categories, and Tags are a lot to wrap your head around, and taxonomies more generally are a huge topic. Amazon even has jobs with “Taxonomist” in the job title!
What I hoped you grasped from the series is that taxonomies are powerful, and, when used well, can greatly improve the way you organize and present information on your website.