Drupal Express is a customized installation of Drupal 7 that is developed and maintained by Institute Communications. It is a means for administrative offices, research labs, groups, special events, faculty members, and student organizations to build their site in Drupal without having to start completely from scratch.
Please note: The new all-in-one campus version of Drupal 8 is also being called Drupal Express. The site below is only relevant to older sites running Drupal 7 Drupal Express.
(Note: If you only need a very simple website, you should consider other solutions, such as Sites at Georgia Tech.)