The purpose of a shock absorber is to take the movement of the suspension and turn it into thermal energy to be absorbed by the hydraulic fluid in the shock. Shocks are separate from the suspension. Shocks limit bouncing and help reduce the front end of the vehicle diving when the brake is used or the back end squatting when the gas pedal is engaged from a stop. Struts are structurally included and a part of the suspension, unlike shocks. Vehicles with struts no longer need upper ball joints or upper control arms. Like shocks, struts perform damping by reducing bounce and noise. Unlike shocks, however, struts help support the suspension as well.