If you ski alpine, you will need a way to let your heel rise while you are climbing (skinning) up. The only way to do this is with Alpine treckers, which pop into your bindings and your boots pop into the trekkers -- they allow your heel to tb free while you walk (like cross country skis), then you take them out for the descent. (www.bcaccess.com/trekfeatures.html
The skins have a hook on the tip and tail and are sticky on the side that touches the base of your skis. Put them on for walking uphill, take them off for descending.
The best kind for the wet snow that you find along the West coast (California, Oregon, Washington) are a synthetic like the ones that Ascension makes. Where the snow is dry (Utah, Colorado, Wyoming), a lot of people like mohair skins. Talk to the people who sell backcountry gear in your area about what is most popular for that region.And take an avalanche course before venturing out into the backcountry. Also, go with a budy who knows what he is doing, or hire a guide who can teach you.