In our recent article on setup_postdata(), a reader posted a good question: how to sort a fetched array of WP_Post objects alphabetically by their terms in a given taxonomy?

A guy named Anh read our article on custom taxonomies and custom fields, and contacted us pointing to a similar article he wrote on his own site. His article’s good—what I like about it, specifically, are the bolded key points on the differences between taxonomies and fields, such as:

We recently used this plugin by the prolific scribu to solve a problem we had: How to migrate an existing WordPress taxonomy (with lots of terms and lots of posts having those terms) to another post type?

This article covers how to add existing taxonomies to a custom post type, and how to make that custom post type show up in those taxonomies’ archive pages.

This article looks at the two major systems for adding data to posts in WordPress: custom taxonomies and custom fields. Since some needs can reasonably by solved by either custom fields or custom taxonomies, we’ll use a practical example—a movie review site—to help define overall principles for when it’s best to use each tool.