You'll find out that Open Wheeler is a catch-all word for purpose made race vehicles with the wheels located outside the car's main body. This is different, in fact, from cars which have their wheel below the body in the manner of most standard street cars. F1 racers are open-wheelers which is the leading race genre as far as open-wheelers are concerned.
The racer's body is enclosed in a minimal open-wheeler cockpit, defining the regular single-seater style, with his head exposed to the air. Behind the racer the motor is positioned, which drives the rear wheels. Most kinds of single-seaters have a very low and virtually even under-tray which helps attain additional aerodynamic downforce that pushes the car onto the track, with wings placed at the front and at the back side of the car.