Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A yaodong is a dugout used as an abode or shelter in China. Yaodongs are common in north China, especially on the Loess Plateau. The history of yaodongs goes back centuries, and they continue to be used. Yaodongs are usually carved out of a generally vertical side of a loess hill. If the side is not vertical, it must be cut vertical. The silty soil is soft and easy to dig. The cross section of a yaodong is similar to that of a cave: a rectangle in the lower part connected to a semicircle in the upper part. The width at the floor is from 3 to 4 meters, and the highest point in the ceiling is around 3 meters or higher. The depth of a yaodong can be 5 meters or more. Windows and doors are installed at the opening of the yaodong. The inner side wall is usually plastered with lime to make it white. A platform called a kang is built to be used as a bed. A fireplace is built beside the kang and the smoke and hot gas go through the built-in channels inside the kang to heat it before exiting through a chimney.