Modules are bundles of primarily PHP code that extend Drupal in order to add new features or alter existing functionality.

Entities are the fundamental building blocks that make up any Drupal site. Having a good understanding of the Entity system is an important part of ensuring the data model of your Drupal site is set up properly.

Patches are used to describe modifications made to one or more code files, and can be used to share those changes.

In order to run a Drupal site, the web server you are using must meet minimum technical requirements.

Tools and workflows for deploying code and configuration changes from one environment to another with Drupal-specific considerations.

The process for keeping Drupal core and contributed modules and themes up to date with the latest security and minor version releases.

Learn about Drupal’s configuration system and how to manage configuration with both the administrative user interface and command-line tools.

Comments are a content entity type that allows users to leave commentary associated with a specific piece of content.

As an open source project, Drupal depends on community contributions in many forms including documentation, code, translation, speaking, organizing events, mentoring others, and even donating money.

A site’s main navigation elements, whether they be in the header, footer, or sidebar, are composed of links built using Drupal's menu system. Drupal allows site administrators to build menus while also allowing module developers to add and alter menus in code.

A layout can describe how various components are arranged on various levels—from an entire page from the header to the footer, to just the “middle” where the dynamic content goes, to individual components. It can apply to templates for managed content or one-off designs for landing pages.

Development environments provide a sandbox where you can work on your application without affecting the live site.

A reliable backup will allow you to restore your site if something goes wrong.

Drush is a command line interface that enables you to interact with your Drupal site without clicking around the graphical user interface (GUI).

Devel is a popular developer module containing a variety of developer and debugging utilities including Webprofiler, Devel generate and Kint.

A block is a reusable widget that is placed inside regions (layout containers) of your theme. Blocks can be used by site administrators on the Block layout admin page or provided by a module using the Plugin API.