Lidar (light detection and ranging) is a remote-sensing technology which uses lasers and GPS (global positioning system) receivers affixed to airplanes to generate precise measurements of the Earth’s surface. By measuring how long a pulse of light from a laser takes to strike the ground or an object and return to the sensor, a computer is able to accurately calculate the distance the pulse travelled. When this is done over a wide area, it is possible to generate very accurate elevation profiles. In this tutorial, you will learn how to navigate and use the GeoInformatics Training Research Education and Extension (GeoTREE) website hosted by the University of Northern Iowa to download lidar data for locations within the state of Iowa.