Events are one of the ways that module developers can alter or extend Drupal without modifying existing code.

Controllers are the portion of a Drupal module that handle responding to an incoming request with the appropriate response data.

Composer is the preferred dependency management solution for PHP, is used by Drupal core, and is becoming increasingly popular for managing the modules and themes used for a Drupal project.

For the Drupal developer, Docker is a way to provide a local development environment to run web server software.

The Render API consists of a standard format for describing data using structured arrays and a process for converting those arrays into the HTML a user sees when interacting with a Drupal site.

Cascading Style Sheets (CSS) files are added as an asset library through a theme’s libraries configuration file. HTML attributes, including classes and IDs, are commonly added in template files with Twig.

In Drupal’s core library there are a number of utility functions and classes that, as a module developer, you will find make your task easier or less tedious.

Drupal's Routing API maps the URL of an incoming request to the code responsible for generating the content that is rendered in response.

Services are objects that encapsulate the code for performing specific tasks in a reusable and decoupled way.

Plugins are one of the ways that module developers can write code that extends Drupal. The Drupal Plugin API allows a module to provide functionality in an extensible, object-oriented way.

Dependency injection is a design pattern commonly used in object-oriented software architectures in order to support Inversion of Control.

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

A content type is a subtype of the [content entity](link to Entity topic). When a content creator goes to add new content to the site, they are presented with a list of content types to choose from to get the appropriate form to fill out.

Drupal's content moderation and workflow tools allow you to configure and support a flexible multistep publication process.

An overview of some of our favorite Drupal documentation resources.

Fields are the building blocks of Drupal's powerful content modeling system. The Field API allows for the development of custom field types to suit almost any data display and collection needs.

Many sites require the ability to upload, manage, and display various assets like files, images, videos, and audio.

A multilingual site has more than 1 language that users interact with, either through the content, the user interface, or both.

Search engine optimization (SEO) is the process of optimizing your online content, so that your content will rank higher in organic (non-paid) search engine results.

Learn to use data from your Drupal site to create customized lists in various forms, such as bulleted lists, grids, calendars, or sliders.