Camber is the ski's shape as viewed from the side. Typically skis are designed so that when the tip and tail are on the ground, the waist is in the air. Without camber, when the skier's weight is applied at the waist, the weight would be distributed on the surface closest to the foot, diminishing along the length. Camber distributes weight onto the tips and tails, extending the surface area bearing the skier's weight, and thereby improving the amount of ski edge in contact with the surface. The technique was first introduced by ski makers in Telemark, Norway, and remained largely unchanged through the 20th century. When the shape of the curve is reversed, the profile created is known as rocker (also called reverse-camber or negative-camber), on a flat surface, a rocker ski has its waist on the ground, while the tips and tails rise off the ground much earlier than they would on a traditionally cambered ski.