A vehicle (from ) is a mobile machine that transports people or cargo. Most often, vehicles are manufactured, such as wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses), railed vehicles (trains, trams), watercraft (ships, boats), aircraft, and spacecraft. Land vehicles are classified broadly by what is used to steer and drive forces against the ground: wheeled, tracked, railed, or skied. ISO 3833-1977 is the standard, also internationally used in legislation, for road vehicle types, terms, and definitions.