Drywall (also called plasterboard, dry lining, wallboard, sheet rock, gypsum board, buster board, turtles board, slap board, custard board, and gypsum panel) is a panel made of calcium sulfate dihydrate (gypsum), with or without additives, typically extruded between thick sheets of facer and backer paper, used in the construction of interior walls and ceilings. The plaster is mixed with fiber (typically paper, glass wool, or a combination of these materials); plasticizer, foaming agent; and additives that can reduce mildew, flammability, and water absorption.

In the mid-20th century, drywall construction became prevalent in North America as a time- and labor-saving alternative to lath and plaster.