Skiing up hill.  Yes, you read correctly - skiing up hill.  That's a new thought in my noggin.  It kind of goes against everything your body feels and your brain thinks.  But that's what you do in backcountry snowboarding.  OK - so not only do I have to learn how to ski, I have to do it uphill.  Hmm.
Skins are sticky on one side, and cloth like on the other side.  There are hundreds of fibers that are designed to grip the snow when you go up the hill, and to let you slide a little when you go downhill.  You put these on right before you head up the trail, and take them off before you head down.  Simple enough concept I guess, but skiing up hill still seems very odd!