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

PHP namespaces provide a way in which to group related classes, interfaces, functions and constants. Drupal uses PSR-4 namespaces to autoload the correct PHP class from a file, accommodating variations in site structures.

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

The Migrate API can be used to import content from an older Drupal site (Drupal 7 or older), or any other data source, into the current version of Drupal.

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.