This document discusses using Drupal to build business applications rather than just websites. It argues that Drupal is a content management platform rather than just a CMS due to its modularity, user management, and other features. Examples of non-CMS applications built in Drupal include e-commerce sites and calendars. The document also describes how Drupal was successfully used to build a large and complex enterprise application, and how its flexibility allowed unanticipated needs to be met. Key Drupal modules for application development include Entity API, Entity Construction Kit, References, and Views.