Ski jumping is a sport in which skiers go down a take-off ramp, jump and attempt to land as far as possible down the hill below. In addition to the length of the jump, judges give points for style. The skis used for ski jumping are wide and long (260 to 275 centimetres (100 to 108 in)). Ski jumping is predominantly a winter sport, performed on snow, and is part of the Winter Olympic Games, but can also be performed in summer on artificial surfaces – porcelain or frost rail track on the inrun, plastic on the landing hill. Ski jumping belongs to the nordic type of competitive skiing.