Drywall is a panel of gypsum board used to form interior walls and ceilings. It is also called sheetrock or plasterboard. It replaced plaster and lath in the mid-20th century because it was faster, cheaper, and easier to install. A drywall panel is a sheet of gypsum sandwiched between two layers of paper. It comes in 4-foot by 8-foot sheets, though other sizes are available. It is fastened to wood or metal studs with screws or nails. The joints are taped and mudded to create a smooth surface.

Drywall comes in several types. Regular drywall is for most interior walls. Moisture-resistant drywall, often green, is for bathrooms and kitchens. Fire-resistant drywall, often Type X, is for garages and furnace rooms. Soundproof drywall is denser and reduces noise transmission. Impact-resistant drywall is for schools and hospitals. The type is specified by the code and the design. The thickness varies too. Half-inch is standard. Five-eighths is used for fire-rated and ceiling applications.

Drywall installation is a trade. The hangers fasten the panels to the framing. The tapers finish the joints with tape and joint compound. The finishers sand the surface smooth. The work is dusty, repetitive, and demanding. A good drywall finish is invisible. A bad one shows every seam and screw. Drywall is not structural. It does not carry load. But it defines the space, hides the wires and pipes, and provides fire and sound separation. It is the skin of the interior. It is everywhere, and it is rarely noticed.