Git from the ground up

There's this recent amazing video about org-mode, that happens to use git internals as the topic of the org mode document. And I just remembered the Aha moments I got when I started grasping git internals.  Here's what made stuff click to me.

- https://www.youtube.com/watch?v=ig5E8CcdM9g
- https://www.youtube.com/watch?v=MYP56QJpDr4
- https://www.youtube.com/watch?v=1ffBJ4sVUb4
- http://ftp.newartisans.com/pub/git.from.bottom.up.pdf


Also, https://initialcommit.io/#baby-git seems like a very nice deep dive into git internals from its core ideas.  I haven't had the time to dig into those articles yet, but worth mentioning them.
And last but not least: A very plain but smart way to investigate git: https://www.reddit.com/r/git/comments/eel2cf/how_does_gitstash_work_under_the_hood/fbubxvz/ . Kinda emacs' "c-h k", but for git.