A catch-all term for purpose built racecars with the wheels located outside the car's main body, as distinct from cars which have their wheels below the body in the manner of most street cars. Formula One racers are open-wheelers, indeed the pre-eminent open-wheeler racing category.
A typical open-wheeler has a minimal cockpit sufficient only to enclose the driver's body, with the head exposed to the air. The engine is located directly behind the driver, and drives the rear wheels. Most types of open-wheeler have wings at the front and rear of the vehicle, as well as a very low and virtually flat undertray that helps achieve additional aerodynamic downforce pushing the car on to the road.
Most open-wheeler races are on dedicated road race circuits. Some major races are held on temporary street circuits, and in the US some are held on oval "superspeedways" - notably the famous Indy track and Indianapolis.
Open-wheeler vehicles, due to their light weight, aerodynamic capabilities, and powerful engines, are, for their cost, the fastest and most exciting to drive racing vehicles available, and the best way for aspiring racers to learn their craft. Virtually all Formula One drivers spent some time in various open-wheeler categories before joining the F1 ranks. However, because the cars do not particularly resemble road cars, and the aerodynamics favour leading drivers over tailing ones thus making overtaking difficult - not to mention the fragility of the cars making the bumping and jostling common in touring and stock car racing impossible - only a few open-wheeler categories draw significant crowds.
Notable categories of open-wheeler racing include: