This recipe creates a route to display the form. By passing the _form variable in the defaults section of our route entry, we are telling the route controller how to render our route's content. The fully qualified class name, which includes the namespace, is passed to a method located in the form builder. The route controller will invoke \Drupal::formBuilder()->getForm (\Drupal\drupalform\Form\ExampleForm) based on the recipe. At the same time, this can be manually called to embed the form elsewhere.

A form builder instance that implements \Drupal\Core\Form\FormBuilderInterface will then process the form by calling buildForm and initiate the rendering process. The buildForm method is expected to return an array of form elements and other API options. This will be sent to the render system to output the form as HTML.