Ski

This article is about the equipment used to slide on snow. For the related activity, see Skiing. For the related activity on water, see Water skiing. For other uses, see Ski (disambiguation).

A shaped alpine ski, showing sidecut—the narrowing of the ski, near the binding.

Skis are runners that are designed to glide over snow. Skiers employ them in pairs, attached to ski boots with ski bindings, with either a free, lockable, or partially secured heel. For climbing slopes, ski skins can be affixed at the base of each ski to prevent them from sliding backwards. Originally used as a means of travel over snow, skis have become specialized for recreational and competitive alpine and cross-country skiing. Skis may also be attached to vehicles, such as aircraft or snowmobiles.