I want to set up time machine but i do not have TONS of space on my external. I keep just the apps and files i use, listen to or watch often on my computer, everything else is on my external. I want to set up time machine but as i said, my space is limited. when time machine backs everything up, does it take up the same amount of space as the origional documents? for example, if i have 40 gigs of stuff on my macbook that i want time machine to backup on my external, will it require 40 gigs of space? or is it just a compressed version of everything? edit, i think i put this in the wrong section, please move if needed.