edia::widget() ](https://developer.wordpress.org/reference/classes/wp_widget_media/widget/) ` wp-includes/widgets/class-wp-widget-media.php ` |  Displays the widget on the front-end.   
[ rest_get_avatar_sizes() ](https://developer.wordpress.org/reference/functions/rest_get_avatar_sizes/) ` wp-includes/rest-api.php ` |  Retrieves the pixel sizes for avatars.   
[ create_initial_rest_routes() ](https://developer.wordpress.org/reference/functions/create_initial_rest_routes/) ` wp-includes/rest-api.php ` |  Registers default REST API routes.   
[ wp_doing_ajax() ](https://developer.wordpress.org/reference/functions/wp_doing_ajax/) ` wp-includes/load.php ` |  Determines whether the current request is a WordPress Ajax request.   
[ WP_Customize_Manager::get_allowed_urls() ](https://developer.wordpress.org/reference/classes/wp_customize_manager/get_allowed_urls/) ` wp-includes/class-wp-customize-manager.php ` |  Gets URLs allowed to be previewed.   
[ WP_Customize_Manager::save_changeset_post() ](https://developer.wordpress.org/reference/classes/wp_customize_manager/save_changeset_post/) ` wp-includes/class-wp-customize-manager.php ` |  Saves the post for the loaded changeset.   
[ get_theme_starter_content() ](https://developer.wordpress.org/reference/functions/get_theme_starter_content/) ` wp-includes/theme.php ` |  Expands a theme’s starter content configuration using core-provided data.   
[ wp_update_custom_css_post() ](https://developer.wordpress.org/reference/functions/wp_update_custom_css_post/) ` wp-includes/theme.php ` |  Updates the ` custom_css ` post for a given theme.   
[ wp_get_custom_css() ](https://developer.wordpress.org/reference/functions/wp_get_custom_css/) ` wp-includes/theme.php ` |  Fetches the saved Custom CSS content for rendering.   
[ get_header_video_url() ](https://developer.wordpress.org/reference/functions/get_header_video_url/) ` wp-includes/theme.php ` |  Retrieves header video URL for custom header.   
[ get_header_video_settings() ](https://developer.wordpress.org/reference/functions/get_header_video_settings/) ` wp-includes/theme.php ` |  Retrieves header video settings.   
[ is_header_video_active() ](https://developer.wordpress.org/reference/functions/is_header_video_active/) ` wp-includes/theme.php ` |  Checks whether the custom header video is eligible to show on the current page.   
[ WP_REST_Users_Controller::check_username() ](https://developer.wordpress.org/reference/classes/wp_rest_users_controller/check_username/) ` wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php ` |  Check a username for the REST API.   
[ WP_REST_Users_Controller::get_collection_params() ](https://developer.wordpress.org/reference/classes/wp_rest_users_controller/get_collection_params/) ` wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php ` |  Retrieves the query params for collections.   
[ WP_REST_Users_Controller::prepare_item_for_response() ](https://developer.wordpress.org/reference/classes/wp_rest_users_controller/prepare_item_for_response/) ` wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php ` |  Prepares a single user output for response.   
[ WP_REST_Users_Controller::prepare_item_for_database() ](https://developer.wordpress.org/reference/classes/wp_rest_users_controller/prepare_item_for_database/) ` wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php ` |  Prepares a single user for creation or update.   
[ WP_REST_Users_Controller::get_items() ](https://developer.wordpress.org/reference/classes/wp_rest_users_controller/get_items/) ` wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php ` |  Retrieves all users.   
[ WP_REST_Revisions_Controller::prepare_excerpt_response() ](https://developer.wordpress.org/reference/classes/wp_rest_revisions_controller/prepare_excerpt_response/) ` wp-includes/rest-api/endpoints/class-wp-rest-revisions-controller.php ` |  Checks the post excerpt and prepare it for single post output.   
[ WP_REST_Revis