Keeping a Drupal site secure requires monitoring security announcements, performing regular updates, and knowing how to properly use Drupal’s APIs to write secure code.

HTML and CSS are the foundational languages for how browsers display web pages.

YAML, which stands for YAML Ain't Markup Language, is a human-readable data serialization format that's been widely adopted in a variety of use cases in Drupal.

Themes provide the HTML, CSS, JavaScript, and other assets that are responsible for the look and feel of your site.

A 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.

Web services allow two or more applications to share data and instructions with one another across the Internet.

Caching 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.

Performance and scalability determine how fast your application can serve a page and to how many users at a time.