Drupal themes
The second type of project is a theme.
What is a theme?
Drupal themes are front-end development projects that leverage the core’s visual system to control the look and feel of the Drupal application. A theme can be the visual presentation of content for end users. It can also be the theme used for the administrative experience of the Drupal application, known as an admin theme.
Themes control the HTML, CSS, and JavaScript used for the Drupal application. HTML is created through the use of templates. Based on the enabled features, content-related features define expected templates that map variables provided by the backend to the corresponding HTML. Templates leverage the Twig framework for functionality and syntax. A theme registers the templates, CSS, and JavaScript, which can then be subsequently enabled in Drupal.
Core themes
The most well-known themes are provided by Core. Core themes provide useful examples for integrating with all core-related...