The steering system controls the position of the front wheels in order to permit the driver to change the direction of the vehicle. Most cars today have power steering, a hydraulic pump powered by a belt connected to the engine that makes steering easier. At one point vehicles did not have power steering, so turning the steering wheel took considerable strength and effort.
Steering begins with the steering wheel. When the driver turns the wheel, the wheel turns the steering column. The column connects to the gearbox where the rotary motion on the wheel is converted to linear motion on the steering linkage. The steering linkage actually turns the front wheels, allowing the driver to steer the car.