A shock absorber generally consists of a
piston that moves through a liquid or through air. By being pushed through the fluid, it changes the
kinetic energy of its movement to heat.
A shock absorber is generally used in conjunction with a spring.
They are not only used on cars, of course, but on all sorts of vehicles - trucks, motorcycles, etc., and even on bicycles.
Shocks and springs act in a manner analogous to certain electronic components.