Residential construction is the business of building and selling individual and multi-family dwellings. The market fragments into single, manufactured, duplex, quad-plex, and apartment and condominium units. Manufactured housing further divides into mobile homes and pre-built houses. In the simplest form, a builder buys a piece of land, develops the land by clearing and grading it, and then constructs roads, sidewalks, drainage, waste removal, electrical and water supplies. Then the builder offers to build either a custom home, a pre-designed home, or a pre-manufactured home, depending on the market they are attempting to serve. In certain instances, the builder may build one or more homes on speculation or "spec", meaning that they build the home without having a buyer ready to buy on the hope that once the house is built, a buyer will appear.