Core

Drupal core is the part of Drupal that ships in the official download of the project named Drupal on Drupal.org. It contains the core modules, core themes, installation profiles and the PHP code under them. Anything you install on top of it is contributed or custom code, and every Drupal site starts from core.

How core is organized in Drupal 11

In the 11.4.10 code, everything sits in a top-level core directory:

• core/modules holds the core modules, for example Node, Views, Layout Builder and Taxonomy. A module such as Node declares package: Core in its info file.
• core/themes holds the core themes, among them Claro, Olivero and Stark.
• core/profiles holds the installation profiles, among them Standard and Minimal.
• core/lib/Drupal holds the PHP classes in the Drupal\Core and Drupal\Component namespaces. The README in core/lib says this directory is for classes original to Drupal, which follow PSR-4 under the vendor namespace Drupal.

Core is also a project with a governance structure. It is divided into subsystems with maintainers, cross-cutting topics such as accessibility and performance, and larger initiatives. Changes arrive as issues, and any core committer may commit a change once it has the required sign-offs.

Example

The two profiles show how much core decides for you. The info file of the Standard profile describes it as an install with commonly used features pre-configured. The Minimal profile is described as a start without pre-configured functionality, suitable for advanced users. Both come from core/profiles, and both run the same core code afterwards.

Common mistakes

• Assuming a feature is core because it is installed on your site. Look at where the module lives. Core modules are under core/modules; a project downloaded from Drupal.org is contributed.
• Staying on a minor release that lost support. The release schedule ends security support for older minors, for example 11.2.x and 10.5.x with the release of 11.4.0. Check your version against the schedule.
• Treating core as one product team. Core maintainers are spread over subsystems and topics, so a request for a change has to find the right issue and the right maintainer.

For marketing and content teams

Core is what your editors get without any extra module: content and fields, menus, Views and user accounts, as the Drupal User Guide lists them. When someone proposes a feature, ask whether it comes from core or from a contributed project, because that decides who maintains it and how it is updated. Core updates follow the public release schedule, so you can plan maintenance windows ahead. The core contributor term explains how people outside the core team get a fix in.

Sources

• Drupal.org: Drupal core project page
• Drupal core 11.4.10, core/lib/README.txt
• Drupal core 11.4.10, Node module info file
• Drupal User Guide: Understanding modules
• Drupal.org: Overview of projects and issues
• Drupal governance: Drupal core
• Drupal.org: Core release schedule