Residential construction is the business of building and selling individual and multi-family dewellings. The market fragments into single-unit, manufactured, duplex, quad-plex, and apartments and condominiums. Manufactured housing further divides into mobile homes and pre-built houses. The business varies primarily in the size and scale of the operations. In the simplist form, a builder buys a peice of land, develops the land by clearing and grading it, and constructing roads, sidewalks, drainage, waste removal, electrical and water supplies. Then the builder offers to build either custom homes or pre-designed homes, or pre-manufactured homes, depending on the market he is attempting to serve. In certain instance the builder may build one or more homes on speculation or "spec" meaning that he builds the home without having a ready buyer on the hope that once the house is built, a buyer will appear.