Laser altimetry is a remote sensing technique used to measure the elevation or altitude of objects or surfaces on the Earth's surface. It involves shooting a laser beam at a target and measuring the time it takes for the beam to bounce back to determine the distance between the sensor and the target. This technique is commonly used in geology, glaciology, oceanography, and atmospheric science to study changes in surface elevation over time, monitor glacier dynamics, and map the topography of hard-to-reach areas. Laser altimetry data can be used to create detailed digital elevation models and help scientists better understand and predict changes in Earth's landforms and ice sheets.