Gypsum board is the generic name for a family of panel-type products consisting of a noncombustible core, primarily of gypsum, with a paper surfacing on the face, back, and long edges. 
Gypsum board is often called drywall, wallboard, or plasterboard and differs from products such as plywood, hardboard, and fiberboard, because of its noncombustible core. It is designed to provide a monolithic surface when joints and fastener heads are covered with a joint treatment system.