The suspension system on any vehicle is designed to increase friction between the tires and the road while absorbing the energy generated for a smoother ride. Connected to the wheels, it helps make the experience inside the cabin more comfortable by insulating the cockpit from impacts.
There are two main components to a suspension mechanism - springs and shocks. The springs control the overall height and load, and the shocks dampen any kinetic energy as the tires rotate over the pavement.
More often than not, the suspension system also includes an anti-sway bar. This allows movement shifts between the wheels and the steering column. In other words, it stabilizes the car and keeps it on the correct path.
Most models have two different suspension systems - one in the front and another in the back. These can be either independent (operating separately from the front/rear axle) or dependent (bound by the axle motion).
Aside from making the experience inside the vehicle more enjoyable, the job of any suspension unit is to prolong the life expectancy of other elements. It cuts down on wear and tear that is generally taken on by rough roads or potholes.