Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.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 are 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. The original Nordic ski technology was adapted during the early twentieth century so that skiers could make turns at higher speeds. New ski and binding designs, coupled with the introduction of ski lifts and snow cats to carry skiers high up on mountains, enabled the development of alpine skis. Meanwhile advances in technology in the Nordic camp allowed for the development of specific skating skis as well as specific ski jumping skis.