Who Is This Handbook For?

The Theme Developer Handbook is a self-contained resource to help you learn the fundamental principles of creating a WordPress theme. It covers a range of topics that span the basics to advanced development.

You should read this handbook if you want to:

  • Create a theme based on nothing but your imagination
  • Build a new theme based on an existing one
  • Extend another theme by creating a child theme
  • Understand how themes work 

Regardless of your reasons for starting down this adventure, this handbook will help you take the next steps toward building a WordPress theme of your own.

Your skill level

While not a strict requirement, you will get the most out of this handbook if you have a baseline understanding and some experience with web technologies, such as HTML, CSS, and PHP. JavaScript knowledge would be a bonus if you plan to add interactivity to the front end.

Present-day WordPress and its block theme system allow you to customize and export a theme directly from the Site Editor interface:

WordPress Site Editor with the options menu dropdown open on the right. The Export option is highlighted.
Exporting a variation of the core Twenty Twenty-Three theme.

With each major WordPress update, its visual building tools become even more robust. Still, having some basic HTML, CSS, and PHP knowledge will help you move along faster.

Unlike block themes, classic themes are built entirely from code. This requires that you be comfortable enough to edit one or more of those languages to some degree.

The Reading this handbook page has more information on the prerequisite knowledge you need to build themes.

At the very least, you must be able to set up and configure a website using WordPress. Otherwise, you won’t be able to test or use the theme that you are building. You can learn more about getting things running in the Tools and setup documentation.

What this handbook covers

This handbook provides the basic information you need to build both block and classic WordPress themes. This includes in-depth coverage of the essential features and APIs that you should know, such as the topics in the Core Concepts chapter. It also dives into tools and techniques for building more advanced themes in the Advanced Topics chapter.

WordPress is a vast subject. HTML, CSS, PHP, accessibility, and other web technologies are even larger. It’d be impossible to cover every aspect of building a website in this handbook alone. Therefore, it is highly-focused on the fundamentals of theme building.

The goal of this handbook is to give you a solid foundation for WordPress theme creation by providing step-by-step instructions for building basic themes and providing resources to further your skills.

If this sounds like something you’d be interested in, come along. You’re in for a journey.