Drupal is made up of many small libraries of code. Composer is the PHP library that helps many PHP projects, including Drupal, manage all those libraries. In Drupal 9 and 10, Composer is used in Drupal core and it is expected that you will use Composer to manage your Drupal site's code.
In this session, we will go over what Composer does and how to use it, especially for Drupal site builders/developers. This includes how to use Composer to add and update modules to your site. We will also touch on more advanced usage such as custom repositories, applying patches, and unmet dependencies. We should have time for questions and sharing your favorite Composer tips and tricks as well.