Concepts

Drupal offers a robust development framework in core that allows for the creation of modules. All types of modules leverage the same framework. A module can be found in core, be contributed to drupal.org, or be a custom module that exists only for a specific use case found in a Drupal application. Use of the framework promotes consistency and helps readily learn across modules.

Modules are set up as projects. Drupal core offers the ability to manage projects per application. This handles the installation, enabling, and disabling of projects. Some projects are intended for specific use cases only, such as debugging on a local system or performing testing on a non-production environment. This allows the same module to exist in a code base but to be managed within a specific application or environment of that application.

As a reminder from earlier chapters, module development should observe the 80/20 rule. Developing Drupal applications starts with site building. Normally...