This is a modification to the suspension to raise the height. This is predominately carried out to SUVs & 4x4s either just for show or for enhanced off-roading performance by allowing an increase in clearance from obstacles on the ground.
Springs: Suspension springs are essentially the connection between the wheels and the body of the vehicle. The main role of springs is to compensate for uneven driving surfaces and in turn provide excellent levels of ride comfort whilst ensuring the wheels have safe contact with the road surface, regardless of condition.
Struts: Struts perform a dampening function much like shock absorbers. The strut is a lightweight and space-saving common dampener type used on many current vehicles, i.e independent suspension, front-wheel drives, and some rear wheel drives also. The strut is a major structural part of the suspension as it takes the place of the upper control arm & upper ball joint that can be found in conventional suspension.
Shock Absorbers: The purpose of shock absorbers is to limit the bounce and sway of the vehicle while driving. Shock absorbers do not support the weight of the vehicle. Shocks absorbers are essentially oil pumps. Inside the shock absorber is a piston, attached by a piston rod. This piston works against the hydraulic fluid in the internal pressure tube. Hydraulic fluid is released through very small orifice holes as the suspension travels up and down, slowing the piston and slowing the movement of the suspension which in turn reduces bounce, roll, sway & squat from acceleration and brake diving.