text: Kart racing or karting is a variant of open-wheel motor sport with small , open , four-wheeled vehicles called karts , go-karts , or gearbox\/shifter karts depending on the design .
simplified: Kart racing or karting is a type of open-wheel motor sport . It uses small , open , four-wheeled vehicles called karts , go-karts , or gearbox\/shifter karts depending on the design .