Note: this post has been moved to the new Drupal-specific section of the site. Read the full post here.
Drupal has a reputation for having a steep learning curve, but I remain convinced that it's largely overstated. Nonetheless, it's true that right from the start the new Drupal user has to contend with documentation that uses unfamiliar, arguably non-intuitive jargon. That said, "What's a node in Drupal?" is a harder question to answer than one might think. Because the pieces of Drupal are usually inter-connected, an easier term to define, like "CCK", depends on the reader understanding what a "node" is. The Views documentation might tell you how to create a Block, but without understanding what each of those things is, it's easy to get frustrated.
So, for the sake of Drupal newbies who want to like Drupal but are struggling to get past the jargon, I've put together my own attempt at some practical definitions, and a diagram of how the pieces link together, at the bottom. My goal here is to make things clearer for the sort of Drupal site developer who will mostly be using the UI; when having choose between technical accuracy and clarity for practical, hands-on purposes, I've sided with clarity. I've organized it in such a way that, with some exceptions, each definition provides prerequisite information for understanding subsequent definitions.