Absolute Beginner's Guide to Drupal

I was doing some surfing and stumbled across this presentation from Drupal Camp Indianapolis in July, 2012.  While the intended audience is people looking to develop websites themselves using Drupal, it does contain useful information for others not familiar with a content management system (CMS), like Drupal, and distinguishes between the most popular Open Source Content Management Systems, namely Wordpress, Joomla and Drupal.