Control arm: A control arm is a suspension component in a car that connects the steering knuckle to the vehicle's frame. The control arm plays a crucial role in ensuring that the wheels stay in the proper position while driving and absorbing shock from the road. It is also responsible for controlling the up and down movement of a car's suspension system.

The control arm is shaped like a triangle and has a pivot, or ball joint, on one end that allows it to move up and down when the vehicle's suspension system is in action. On the other end, the control arm is attached to the car's frame with bolts. The position of the control arm also plays a role in preventing undesirable movements like rolling or swaying. Without the control arm, the car's suspension system would not function properly, leading to poor handling, uneven tire wear, and a bumpy ride.