Surveying or land surveying is the technique, profession, and science of determining the terrestrial or three-dimensional position of points and the distances and angles between them. These points are usually on the surface of the Earth, and they are often used to establish maps and boundaries for ownership, locations like building corners or the surface location of subsurface features, or other purposes required by government or civil law, such as property sales. It is also used in transport and communications.

Surveying work is done using elements of geometry, trigonometry, regression analysis, physics, engineering, metrology, programming languages and the law. They use equipment such as total stations, robotic total stations, GPS receivers, retro reflectors, 3D scanners, radios, handheld tablets, digital levels, subsurface locators, drones, GIS and surveying software.

Surveying is used for geodetic control and survey monumentation, computer-based solutions for coordinate systems transformation, precise surveys of construction and engineering projects and setting out, digital map preparation, profile and grid leveling and contour maps, earth volume computations, deformation and settlement monitoring.