Through my time in the "Drupal Careers Online" course through DrupalEasy, my eyes have been opened to the wonderful world of entities, bundles, and fields. This has been such a game changer! Drupal's Entity API is one of the key elements that sets it apart from other CMS systems. Defining a site is so much easier once you understand the "building blocks" (i.e., entities, bundles, and fields), specifically "ContentEntityBase" and entities that extend it.