Cross-country skis are very light and narrow, and usually have quite straight edges, though some newer skis have slight sidecut. The boots attach to the bindings at the toes only. There are three binding systems currently used, Rottefella's NNN and Salomon's SNS profil and SNS pilot. The ski bases are waxed to reduce friction during forward motion, and kick wax can also be applied to get adhesion when going uphill. Some waxless models may have patterns on the bottom to increase the friction when the ski slides backward. There are two major techniques, classical (traditional striding) and freestyle or skating which was developed in the 1980s. Skating skis are shorter than classical skis and do not need grip wax. Skating is also the technique used in biathlons.
