Drupal 8 is here and so is the new theming engine powered by Twig. As Drupal themers new to D8, we’ll begin to learn the new syntax and evolve to configuring our themes with .yml files. Along with these API changes, there are also new conceptual changes that, maybe, haven’t garnered the same level of attention. This article will help with the introduction and concepts of libraries in Drupal 8’s new theming layer.