Wallboard is a kind of board made of gypsum and paper or of fibers of wood, cane, or other materials. It is used to cover large areas such as walls and ceilings. Wallboard gives protection against fire and weather, and insulation against heat and cold. It absorbs sound and also serves as a decoration. Wallboard is made in sheets 1/10 inch to 3 inches (2.5 to 76 millimeters) thick. It is made in sections up to 8 feet (2.4 meters) wide and 20 feet (6 meters) long. A wall that has its surface covered with wallboard is called a dry wall. A type of wallboard called plasterboard, often sold under the trade name Sheetrock, has a core of gypsum sandwiched between layers of heavy paper.