Although motor-sport is generally used to refer to high-speed cars and the men that drive them, it can also include other vehicles. Motorboats, Motorcycles and air racing can all fall into the category of motor sport- all involve vehicles driven at a tremendous speed.
The most popular form of motor racing would have to be auto racing; that is racing cars. The first known organized race took place in Paris, organized by magazine le Pent Journal. As more and more people bought cars, more and more people partook in motor-sport. Races were usually organized across cities, sometimes even across countries. The first trophy awarded for racing in Europe was the Gordon Bennet Cup, as motor-sport travelled to the United States of America they brought about the Vanderbilt Cup.
While auto racing was banned in 1903 because of a succession of deaths, it soon came back into popularity in the 1930s. As more and more people started to watch racing, large car companies began to get involved- the likes of Bugatti, Mercedes-Benz and Delage all producing cars that could be used to race with. Even with the 1955 Le Mans disaster (where by accident a car flew into the spectators, and the driver along with eighty people were killed) racing continued to rise in popularity and is now one of the most watched spectator sports in the world.
There are many different types of car racing, the most common ones are single seater racing (Formula One, the most watched racing tournament in the world is based on this), stock car racing (NASCAR is an example), drag racing (popular among those who race unofficially on the streets) and kart racing, which anybody can do at go kart centres. Famous racers like Michael Schumacher and Fernando Alonso all practised kart racing when they were young children- as young as a mere five years old.
As for other types of motor-sport, motorbike would be considered the second most popular motor-sport after auto racing. One of the most successful motorbike racers of all time is currently racing in the modern era, he is the great Valentino Rossi (who has won seven Grand Prix Championships. Although the most well known form of motorbike racing is on tarmac or “track racing”, it can also be done off-road such as MotoCross. MotoCross has a number of different events- it can be performed on sand, snow and grass and racers must be used to all surfaces if they want to do well.
As for motorboat racing, there is F1 Powerboat Racing. Similar in rules to Formula 1, the obvious different is that this takes place on water and not land. Air racing is the least popular out of the four kinds of motor-sport, although as planes get faster and faster it will no doubt reach their level at some point in the future.