DEM, or Digital Elevation Model, is a 3D representation of a terrain's surface created from terrain elevation data. It is commonly used in geographic information systems (GIS) to analyze landforms and topography. DEMs can be generated from various sources, including satellite imagery, aerial surveys, and LiDAR technology. These models are essential for applications such as urban planning, environmental studies, and disaster management. By providing detailed information about elevation, DEM helps in understanding water flow, identifying flood zones, and planning infrastructure projects.