we created a custom Field Type (data storage) and built a Field Widget (data input).

Now we complete the field system by building the final layer: Field Formatters.

In the previous topic, we created a custom Field Type, which defined how data is stored and structured. Now we move to the next layer of the field system: Field Widgets.

Fields are one of Drupal’s most important backend concepts. They define how data is stored, validated, and exposed across entities.

Blocks are one of the most visible features in Drupal, but behind the scenes they are powered by a plugin system.

Drupal’s AJAX API allows parts of a page or form to update without a full page reload. It is built directly into the Form API (FAPI) and tightly integrated with render arrays, routes, and controllers.