Control arms are the foundation of your front suspension system. In basic terms, control arms are the connection that links your front wheels to your car. One end of the arm connects to the wheel assembly and the other end connects to the framework of your car.
The upper control arm connects to the uppermost area of the front wheel and the lower control arm connects to the lower most area of the front wheel, with both arms then attaching to the frame of the car. If you have independent rear suspension, the design is similar.