The document discusses leveling, which is the art of determining the relative heights of points on or below the earth's surface. It describes the instruments used for leveling including levels, leveling staffs, and tripods. It also discusses the different types of levels, methods of leveling, classifications of direct leveling, terms used in leveling such as station, backsight, foresight, and benchmarks. It provides information on computing reduced levels using either the collimation method or rise and fall method.