A shock absorber dampens the spring movement so that there is a constant contact between the tires of the car and the road surface.
A shock absorber consists of a cylinder containing a hydraulic fluid or gas. In this cylinder is a piston that goes up and down because it is in direct connection with the movement of the wheels. The cylinder has internally small openings through which the gas or liquid can flow in and out of the cylinder. Due to the resistance when the liquid or gas flows through these openings, the spring movement is damped. The speed at which the liquid or gas can flow through the openings determines the damping force.
A worn shock absorber can negatively affect the road holding of the car. The contact between the tires and the road surface will then no longer be optimal. This means that fewer shocks are absorbed, road contact is less and grip is lost.
The life span of a shock absorber depends on your driving style and the type of road surface where you drive the most. The impact of the shock absorbers gradually deteriorates, often without noticing it. Shock absorbers are always replaced per set to keep the car in balance.