One of the main outcomes of Drupal 8 was "getting off the island" with third-party code included in core and adopting modern best practices from the wider PHP ecosystem - including Composer, PHP's dependency manager. Included to manage core's dependencies, it has also gained traction in the contrib space with the creation of the Drupal Composer project, and the Drupal Packagist and now native endpoints on Drupal.org exposing contrib project metadata. In this session, we'll learn how to fully manage a Drupal 7 or Drupal 8 website including contributed modules and themes and external libraries with Composer.