Speed skating is a competitive form of ice skating in which the competitors race each other in travelling a certain distance on skates. Types of speed skating are long-track speed skating, short-track speed skating, and marathon speed skating. In the Olympic Games, long-track speed skating is usually referred to as just "speed skating", while short-track speed skating is known a "short track". The International Skating Union (ISU), the governing body of competitive ice sports, refers to long track as "speed skating" and short track as "short track skating". Long track speed skating takes place on a 400 m ice track, while short track takes place on a 111 m track.