Any kind of material placed under carpet to provide softness and adequate support when it is walked upon. Carpet cushion provides a softer feel underfoot and provides added acoustical and insulation benefits and longer wear life for the carpet. In some cases, the carpet cushion is attached to the carpet when it is manufactured. Also referred to as "padding" or "underlay," although "cushion" is the preferred term. Cushion under most residential carpet should be a thickness no greater than 7/16".