Drupal has become the system of choice for many smaller and larger projects. Since I am receiving from time to time questions about the system and what it is and does I think the following video introduction could be helpful. In this introduction the authors of the book "Using Drupal" explain all important aspects  of the system.

Especially the comparison to other systems might answer a lot of the questions I hear quite often (short side notice: this is the first time I try youtubes deep-link option). The audio is not perfect but sufficient.