The `add_theme_support()` function in WordPress allows developers to register theme support for specific features by calling it in the theme's `functions.php` file
The `add_term_meta()` function in WordPress allows developers to add custom metadata to a specific term by specifying its ID and the key/value pair of the metadata they wish to add
The `add_site_meta()` function in WordPress allows adding custom metadata to a specific site using its ID, meta key, value, and optionally making it unique
The `add_settings_section()` function in WordPress allows developers to create custom settings sections and fields for their website's administrative interface