A ski is a long flat device worn on the feet designed to help the wearer slide smoothly over snow. Originally intended as an aid to travel in snowy regions, they're now primarily used for recreational and sporting purposes. Also, a ski may denote a similar device used for other purposes than skiing, for example, for steering snowmobiles. Snow skis glide on snow because downward pressure, as well as heat from surface friction, melts a thin layer of snow directly under the ski. This creates a ve… (More on Ski)