A disc sander is most commonly known as a stationary machine that consists of a replaceable circular shaped sandpaper attached to a wheel being electrically spun around. The usually wooden work piece, (although other materials can be shaped and worked on such as plastics and other soft materials, even aluminum), is sat on a front bench that can be adjusted to various angles. It can be used for rough or fine sanding depending on the sanding grit used. [via wikipedia]