Your car's engine produces a tremendous amount of heat when it's running. That heat must be constantly transferred and removed or overheating could result. The radiator and water pump are the main components that take care of removing heat from the engine. Your car's water pump moves fluid through the engine where heat's absorbed. Then the fluid goes to the radiator where it's cooled. The thermostat controls the flow of fluid through the engine and radiator. Your car's engine needs to be somewhat warm to work efficiently. Cold engines may waste fuel, but if they get too hot, they could overheat. Lights or gauges on the dashboard should provide a warning if the car's running too hot or cold. If the warning light comes on, or the temperature gauge moves to the red area while you're driving, it may be a good idea to pull over and try to find out what's wrong. Contact a qualified mechanic for more information on your car's cooling system.