Xdebug
TopicDebugging your Drupal codebase can be made substantially easier by learning how to enable and configure the Xdebug PHP extension.
Caching in Drupal
TopicCaching in Drupal is controlled by Drupal's Cache API which is used to store any type of data on a permanent or temporary basis. Some types of data tend to take a long time to compute, but utilizing the Cache API in your module can help your site load data more quickly.
Learn about resources to guide you through the process of updating a module or theme to the latest version of Drupal.
Themes provide the HTML, CSS, JavaScript, and other assets that are responsible for the look and feel of your site.
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.
Drupal Core Modules
TopicA module is a set of PHP, JavaScript, and/or CSS files that extends site features and adds functionality. The Drupal core software comes with a set of modules that provide a range of features.