This article is based on the O'Reilly article which is relevant to Drupal7 and some of it for Drupal8, but drupal did a lot of modifications since then, and I believe it's a good place to start with, but still should be modified to Drupal9 and on. from time to time I will fix this article and update it according to the last drupal version, you are all invited to send me remarks and suggestions.

These examples, I believe are most needed for the more advanced Drupal backend developer.

My development strategy recommendations are: