Formula racing, also known as open-wheel racing in North America, is any of several forms of open-wheeled single-seater motorsport. A "formula", first devised by FIA for its post–World War II single-seater races, is a set of regulations for a given type of car. The best known are Formula One, Formula E, Formula Two, Formula Three, regional Formula Three and Formula Four. Common usage of "formula racing" encompasses other single-seater series, including the IndyCar Series and the Super Formula Championship.
Lower categories such as Formula Three and Formula Two are described as junior formulae, lower formulae, or feeder formulae, referring to their position below top-level series like Formula One on their respective career ladders of single-seater motor racing. There are two primary forms of racing formula: open formula, which allows a choice of chassis or engines; and control or "spec" formula, which specifies a single supplier for chassis and engines. Formula Three is an example of an open formula, while Formula BMW is a control formula. Exceptions include Formula Ford, which has an open chassis formula but a single-brand engine formula.