The first thing to understand about Drupal is that it is based on a modular approach to providing functionality. I will elaborate on this further in another post.

The point I want to focus on in this post is that every module on a Drupal site is a first-class citizen. There are no "special" modules that can so something that other modules cannot do.

Three basic types of modules are:

1. core
2. contrib
3. custom

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