Drupal.org (aka: dee-dot-oh)
https://www.drupal.org/
The Drupal project’s official website.
Planet Drupal
https://www.drupal.org/planet
Planet Drupal aggregates blog posts from the Drupal community. It is often a great source of information. There is a Planet Drupal RSS feed for those still using RSS readers.
Drupal at your fingertips
A great online reference maintained by Selwyn Polit.
https://selwynpolit.github.io/d9book/
Drupal 9: Selecting Machine Names For Content Entities And Fields
Philip Norton, #! code
https://www.hashbangcode.com/article/drupal-9-selecting-machine-names-content-entities-and-fields
Drupal 9: Loading All Routes From A Module
Philip Norton, #! code
https://www.hashbangcode.com/article/drupal-9-loading-all-routes-module
Major Drupal configuration schema cheat sheet update
Gábor Hojtsy, Gábor Hojtsy on Drupal
http://www.hojtsy.hu/blog/2021-dec-22/major-drupal-configuration-schema-cheat-sheet-update-7-years-later
The Typed Data API, by example
Matt Glaman, Dec 31, 2021
https://mglaman.dev/blog/typed-data-api-example
Managing lists in Drupal
Murray Woodman, Morpht, Feb 13, 2022
https://www.morpht.com/blog/managing-lists-drupal
Drupal 9: The Correct Way To Redirect A Page
Philip Norton, #! code, May 22, 2022
https://www.hashbangcode.com/article/drupal-9-correct-way-redirect-page
Drupal 9: Creating A Category Menu Using Derivers
Philip Norton, #! code, Aug 14, 2022
https://www.hashbangcode.com/article/drupal-9-creating-category-menu-using-derivers