Ski geometry is the shape of the ski. Described in the direction of travel, the front of the ski, typically pointed or rounded, is the tip, the middle is the waist and the rear is the tail. Skis have four aspects that define their basic performance: length, width, sidecut and camber. Skis also differ in more minor ways to address certain niche roles. For instance, skis for moguls are much softer to absorb shocks from the quick and sharp turns of the moguls and skis for powder are much wider to provide more "float" in deeper, softer snow.
Different geometry at skis for backcountry skiing (top), allmountain skis and piste skis for carve turns.
Modern powder skis are much wider than on-piste designs. This example has noticeable rocker shaping at the tip and tail, while retaining some camber and sidecut.
Visible hourglass shape at parabolic skis.
Parabolic skis for slalom racing (left) and for piste carving (middle), skis with little sidecut for giant slalom racing (right).
A ski is a narrow strip of semi-rigid material worn underfoot to glide over snow. Substantially longer than they are wide, and characteristically employed in pairs, skis are attached to ski boots with ski bindings, with either a free, lockable, or partially secured heel. For climbing slopes, ski skins can be attached at the base of the ski.
A shaped alpine ski with relatively little sidecut and classic camber: the tip and tail touch the snow while the midsection is in the air.
Old skis
Asymmetrical skis used by the Danish-Norwegian army in the 18th century, long ski for the right leg, also shown in profile (far left).
Wooden skis with cable (kandahar) bindings and bamboo poles