Drush (the Drupal Shell) is a command line interface for Drupal. It provides all sorts of commands for assisting in Drupal development, automating workflows and in general making it easier to script various parts of the Drupal workflow. Learning to use Drush and the commands that come with Drush core will help both site administrators and developers speed up their day-to-day Drupal work. It really is a handy tool for everyone, not just developers. We've just published a whole new series of tutorials on Drush, representing a huge effort to bring our Drush content up-to-date.