How Do Shock Absorbers Stop An Automobile From Continually Bouncing?

Shock absorbers use a fluid to reduce the "bounce" of the spring inside your shock absorber.

The use the idea of damping and damped oscillations: the elastic force is reduced quite rapidly (green line) by the action of a damping force that antagonize the elastic force and reduce the amplitude of oscillation.


The spring of the shock absorber is coupled with a fluid (oil for example) that dampens the oscillation basically not allowing the spring to keep on bouncing".
Consider the diagram:

When the piston is lowered and compresses the spring the valves allow the passage of the fluid; on return the valves close making difficult for the fluid to pass and for thespring to return and bounce back.