Can either be left-handed or right-handed, which has to do with what side the crank is on relative to the blade and handle. Although I think the new safety can openers are ambidextrous.

Can openers can also be electric, but that is an abomination of all that is good. Unless you have trouble using your hands due to paralysis, arthritis or carpal tunnel syndrome, the elecricity used to open a can could be better spent doing something else, and besides, you probably need the excercise. On top of all that, it's usually faster to use a hand can opener than a machine. Really.