The git checkout [filename] behaviour always confused me.. Yes, it's documented, but git seems to really try and make it difficult to lose any work.. but has a

The git checkout [filename] behaviour always confused me.. Yes, it's documented, but git seems to really try and make it difficult to lose any work.. but has a command that makes it simple to irreversibly lose your upstaged changes, without so much as a warning? At least "git revert" sounds like it might undo changes.. In what way does "checkout" imply both "checking out" branches, and reseting a file to it's previously commited state?