There are two main types of surveying: plane surveying and geodetic surveying. Plane surveying considers the earth's surface to be flat and neglects curvature, while geodetic surveying takes curvature into account. Surveying can also be classified based on the nature of the field, such as land, marine, or astronomical surveying, as well as based on the instruments or methods used, including chain, compass, plane table, theodolite, tacheometric, and photographic surveying.