Lidar (, also LIDAR, or LiDAR; sometimes LADAR) is an acronym of "light detection and ranging" or "laser imaging, detection, and ranging". It is a method for determining ranges by targeting an object or a surface with a laser and measuring the time for the reflected light to return to the receiver. It is sometimes called 3-D laser scanning, a special combination of 3-D scanning and laser scanning. LIDAR has terrestrial, airborne, and mobile applications.

Lidar is commonly used to make high-resolution maps, with applications in surveying, geodesy, geomatics, archaeology, geography, geology, geomorphology, seismology, forestry, atmospheric physics, laser guidance, airborne laser swath mapping (ALSM), and laser altimetry. It is used to make digital 3-D representations of areas on the Earth's surface and ocean bottom of the intertidal and near coastal zone by varying the wavelength of light. It has also been increasingly used in control and navigation for autonomous cars and for the helicopter Ingenuity on its record-setting flights over the terrain of Mars.