What is -a in git commit -am "msg"

What is -a in git commit -am “msg”? I saw it in the hint

From git’s commit documentation page:


Tell the command to automatically stage files that have been modified and deleted, but new files you have not told Git about are not affected.

Basically, you don’t have to run git add before your commit. But any files that git does not know about yet (stuff you just created), won’t be commited.