I thought it was a very sophisticated system of file version management that very carefully measured deltas between versions of files, and stored only those deltas. If you believe this, you'll experience nothing but grief with Git, because that's not what it is.
It actually stores everything you tell it to, and can optionally compress it down to deltas. The storage at the root is all content based, instead of file name based, so if you have 5000 different names for the exact same 1 megabyte of stuff, you'll only store it once, along with all the names (and other metadata it uses internally).
Even Linus Torvalds only really uses a few commands.
> Torvalds described himself as a casual user of Git who mainly uses just five commands: git merge, git blame, git log, git commit and git pull – though he adds later in the interview that he also uses git status “fairly regularly.”
SCCS, RCS, SourceSafe, Vault, TFS, git. Use the gui if you can.