For questions generally about motor racing that takes place on a paved hard surface, as opposed to off-road racing. For questions about the class of bicycle racing, see 'road-biking'. For running races on city streets, see 'marathon'.
Road racing is generally defined as a form of racing for which the primary raceway is a hard, paved surface, often called a "track" if the surface and venue are designed solely for this type of event. This is opposed to "off-road" or "dirt track" racing where the surface is loose dirt, or "cross-country" racing where the competitors travel across natural terrain for long distances.
Other than marathon running, which typically takes place on paved streets, and road bicycling, featuring several well-known races including the Tour du France, most road racing involves motor vehicles. Well known motor racing associations include:
NASCAR, the National Association of Stock Car Auto Racing, which sponsors a series of races primarily on oval tracks for teams of professional drivers and maintenance crews using purpose-built closed-wheel cars. The primary championship series is the Sprint Cup Series, formerly the Winston Cup, with the Nationwide Series also held as a "minor league" series with reduced-horsepower cars, attracting junior racers looking to enter the Sprint Cup. NASCAR is the most popular spectator motor sport in the United States.
IRL, or the Indy Racing League, currently the primary North American open-wheel racing league. This league sponsors well-known races throughout the US and Canada, including oval-track races like the Indy 500 and circuit-track races on proving ground circuits like Laguna Seca and street courses like in Toronto. Drivers often use this league as a stepping stone to or from NASCAR or Formula 1 racing.
FIA, the Fédération Internationale de l'Automobile, which is the primary governing body for international motor racing classes. The FIA oversees the top international open-wheel racing class, Formula 1, as well as Formula Two, GT1, GT3, rally and touring car championships, and numerous smaller events such as hill-climbing, drag racing and autocross. Formula 1 is the most popular spectator motorsport in most of Europe and South America.
IMSA, the International Motor Sports Association, a competing association to the FIA, overseeing several closed-wheel classes including the American Le Mans Series, two GT3 classes, and several smaller classes using manufacturer-specific car designs, including Formula V and Formula Ford.
NHRA, the National Hot Rod Association, which is loosely affiliated with the FIA and oversees most classes of straight-line drag racing in the United States and Canada.