Drupal is a great content management system (CMS). To understand why I personally use Drupal, you should probably first understand my background. I went to school for graphic design, so I got a Bachelors degree in Fine Arts. This didn't teach me much about how to use programs, but how to think about the design process. Most of the technical side of what I do had to be picked up on my own.
Here are some things I have found to be useful:
People who are new to Drupal are always asking "What are your must-have modules?" Everyone has their own answer, but as many times as I have heard this question asked, two modules always remain. VIEWS and CCK.
