Kart racing or karting is a variant of open-wheel motorsport with small, open, four-wheeled vehicles called karts, go-karts, or gearbox/shifter karts depending on the design. They are usually raced on scaled-down circuits. Karting is commonly perceived as the stepping stone to the higher and more expensive ranks of motorsports.

Karts vary widely in speed and some (known as Superkarts) can reach speeds exceeding 160 miles per hour (260 km/h), while go-karts intended for the general public in amusement parks may be limited to speeds of no more than 15 miles per hour (24 km/h). A KF1 kart, with a 125 cc 2-stroke engine and an overall weight including the driver of 150 kilograms has a top speed of 85 miles per hour (137 km/h). It takes a little more than 3 seconds to go from 0 to 60 mph with a 125 cc shifter kart (6 gears), with a top speed of 115 miles per hour (185 km/h) on long circuits.

Kart racing is usually used as a low-cost and relatively safe way to introduce drivers to motor racing. Many people associate it with young drivers, but adults are also very active in karting. Karting is considered the first step in any serious racer’s career. It can prepare the driver for high-speed wheel-to-wheel racing by helping develop quick reflexes, precision car control, and decision-making skills. In addition, it brings an awareness of the various parameters that can be altered to try to improve the competitiveness of the kart (examples being tire pressure, gearing, seat position, chassis stiffness) that also exist in other forms of motor racing.
All current (with the exception of Russian driver Vitaly Petrov) and many former Formula One drivers grew up racing karts, most prominent among them, World Champions Michael Schumacher, Ayrton Senna, Alain Prost, Fernando Alonso, Kimi Räikkönen, Jenson Button, Lewis Hamilton and Sebastian Vettel. Many NASCAR drivers also got their start in racing from karts, such as Darrell Waltrip, Lake Speed, Ricky Rudd, Juan Pablo Montoya, Tony Stewart, and Jeff Gordon.

In August 2009, in anticipation to a possible return to F1 with Ferrari, Formula One world champion Michael Schumacher did some preparation driving a kart in Lonato, Italy. Schumacher also raced at the SKUSA SuperNationals, an event taking place each year in Las Vegas, along with F1 drivers Sébastien Buemi and Nelson Piquet, Jr. Felipe Massa also used karting in September 2009 to test his condition in Brazil, two months after his Hungarian Grand Prix freak accident during qualifying.

(Source Wikipedia)