How it works...

In Drupal, there are entities that have bundles. A bundle is just a type of entity that can have specific configurations and fields attached. When working with nodes, a bundle is generally referred to as a content type.

Content types can be created as long as the Node module is enabled. When a content type is created through the user interface, it invokes the node_add_body_field() function. This function adds the default body field for content types.

Fields can only be managed or added if the Field UI module is enabled. The Field UI module exposes the Manage Fields, Manage Form Display, and Manage Display for entities, such as nodes and blocks.