Drywall panels cover most walls and ceilings built over the last 40 years. Also called sheetrock, wallboard, or gypsum board, drywall is made of a layer of gypsum sandwiched between heavy paper facings. A waterproof type, sometimes called "green board" because of the color of the paper, is used in bathrooms and other areas subject to heavy moisture. Drywall installation is so common because it is simply the best material for the job on the market. It is far less messy than plaster (which used to be the standard) and less expensive than wood paneling. After you install drywall in your home, you have a surface that can be easily modified to look a variety of different ways, and you haven't spent a bundle, either!