Although Drupal is often described as a "content management system" (CMS) it is also a "content management framework" (CMF). In other words, unlike a typical CMS, it is geared more towards configurability and customization. Picture a range of measurement where one end of the scale is labeled “specific” and the other end “abstract”. On the “specific” end of the spectrum, you would have something whose form is very specialized because it’s meant for a specific purpose—like, say, a hammer. On the other end of the spectrum, you would have something much more abstracted, that is available to be configured any way you like, for a variety of purposes—like some wood and a chunk of steel. You could make a hammer, or any number of other things with the wood and steel.
Of course, while chunks of wood and steel are more “configurable” than a hammer, they aren’t terribly useful because few people have the specialized knowledge to work with such raw materials. Drupal’s purpose is to sit in the sweet spot between the two ends of the scale, and create a sort of “builder’s kit” made up of pre-designed components that can be used as-is or can be extensively reconfigured to suit your needs. Its design provides incredible flexibility while still allowing people who aren’t programmers to make powerful websites. This principle of manageable abstraction is important to understand, because it is a central concept to all things Drupal. When you understand why a measured amount of abstraction is valuable, you’ll begin to understand why this approach is such a strong argument for using Drupal.
