What is the main purpose of a vehicle's suspension system (shocks and struts)?

The suspension system — including springs, shock absorbers, and struts — absorbs bumps and vibrations from the road, cushions the ride, and keeps the tires in firm contact with the road surface for traction, handling, and braking. Shock absorbers (shocks) dampen the bouncing of the springs, while struts combine a shock with a structural support. Worn shocks cause excessive bouncing, longer stopping distances, and uneven tire wear. The suspension's job of smoothing the ride and maintaining tire contact is a standard topic on the brakes-and-suspension portion.