Technologies that drive Drupal
Drupal has gone through a series of different best practices for when it comes to how it should be installed. But the reality is that they are simply tailored to different needs. The most common, and the most recommended by this author, is the Composer-based approach with the Drupal community-promoted project here: https://www.drupal.org/docs/develop/using-composer/starting-a-site-using-drupal-composer-project-templates.
You can read more about how to install Drupal there, so I will not go into details here. Instead, let's talk a bit about the technologies that power (or are needed by) Drupal 9.
PHP
Drupal is written in the PHP programming language. PHP is a widely supported, multiplatform, and web-centric scripting language. Since Drupal is written in PHP, this book will largely feature code written in PHP, albeit with Drupal standard practices being kept in mind.
It is very important to note that the minimum version of PHP required...