This article will discuss how to register fields and field groups via the functions.php file. There are many benefits to using PHP to register fields, the main of which is customization and distribution. The ability to define fields within the theme’s files allows developers to avoid any data loss when working across multiple environments (dev/staging/live). It also reduces calls to the database and can speed up your website.

If you only require a solution for distribution across multiple environments, please familiarize yourself with the local json feature as this solves the issue with minimal effort.