A damper is a heating and cooling accessory that is used with ductwork. Their primary responsibility is to regulate the air flow to a zone, or room, in the home. Depending on the damper you select, either a circular or rectangular plate at the center of the damper will open or close to permit or block air flow. When a damper blocks air flow to a zone, that air is then pushed into other areas of the home. Zones, with open dampers, heat quicker but with less work from the furnace.