"Advanced Custom Fields" (ACF) is a plugin for WordPress that provides web developers with the ability to create and manage customized data fields on WordPress sites. These features go beyond the default features of WordPress, allowing for the creation of more complex and customized content types on sites.

ACF allows users to create custom field types such as text boxes, file uploaders, image pickers, radio buttons, date pickers and many more. These fields can be easily added and managed through the WordPress admin panel. For example, if you run a news site, you can add custom fields such as "Publish Date", "Author" or "Source" for each news article.

ACF can be integrated with WordPress themes and plugins, so developers can use custom data fields in their themes and plugins. In short, ACF increases the functionality and flexibility of WordPress sites, delivering richer and more user-friendly experiences. With this powerful tool, websites can go beyond the standard WordPress installation and become more customized and functional.