This is the first "AB Abridged" post – a series of posts explaining the basics of some of the more ominous yet awesome Drupal projects in simple and practical terms. We hope these posts will help demystify some of these projects for people who have been hesitant to try them out!
Background
The previous version of Aegir, called Hostmaster, was developed by Adrian Rossouw (g.d.o member 1337 coincidence...?) for use at the now defunct Bryght, where they did mass Drupal hosting for several years. Its main components are the provisioning system, which manages some of the server side and back end configuration, and the hosting front end, which allows you to treat each site as a node and manage it through a Drupal interface. The hosting system also handles and allows you to watch the status of queued tasks on the server. 
Screenshot of the admin interface c/o Dev Seed
