Where does a checkout come from?

In other words, when you do git checkout 3256678, exactly what "place" do the files and directory structures they might have been in when you did the commit 3256678, come from to populate your Working Directory. By "Working Directory", I mean where you can use ls to list them, emacs to edit them, rm to delete them, manipulate them with zfs, etc.. And "from" means The Index, The Working Tree, The Object Store. I am a newbie, so please try to make your answer as simple as possible. My feeling is that the Object Store holds that commit, and when you check it out, you just get a copy of the tag, commit, tree, and blob(s) from what is in the Object Store. Thanks!

Last updated 8 years ago

What led me to this question was a post I saw at the link below that showed checkout originating at Index and Object Store. From Index it was git checkout . and from Object Store it was git checkout HEAD I take it the git checkout . uses the last commit kept in the Index. Still not really clear on what the Working Tree is!