I always question why "Shock Absorbers" are so named because that's not what they do!
Shock is absorbed by the spring, the "misnamed article" is there to stop the spring reciprocating (going boing, boing, boing in technical terms) i.e. as a damper to the spring.
IMHO they really should be called "Dampers" and I'm sure they used to be years ago.
Therefore, the damper is designed to compress without restriction (to allow the spring to absorb the shock) and then to restrict extension again, usually by the use of oil being forced through a small hole, thus slowing down the speed that it extends.
Of course, technology has developed on this basic principle and the use of gas, internal springs, multiple chambers, external chambers and the like makes them more complex, but they are still basic dampers to stop uncontrolled bounce in the springing of the vehicle.
I'm sure that there's many on this site that would have explained all that much better than me, but I'm sure I'm right in this basic approach. Any opinions?