difference between cc by 3.0 and cc by sa 3.0??

difference between cc by 3.0 and cc by sa 3.0??

i'm kind of a noob about licenses and their instructions, and most (if not, all) of the work i've been using have cc by 3.0, cc by sa 3.0 and cc0 licenses, i get what cc0 means but i dont get what the difference between cc by 3.0 and cc by sa 3.0, any clarification would be appreciated!