Remote sensing is the art and science of making measurements of the earth using sensors on airplanes or satellites. These sensors collect data in the form of images and provide specialized capabilities for manipulating, analyzing, and visualizing those images. Remote sensed imagery is integrated within a GIS. Remote sensing and geographic information systems are of particular interest to geographers. Remote sensing involves imaging of the Earth from aircraft or spacecraft at scales ranging from a few square kilometers to the entire globe. Images are formed from visible light as well as near-infrared light, thermal radiation, and microwave radiation, and thus extend well beyond the range of the human eye. The science of remote sensing involves extracting information from these images—for example, mapping vegetation properties over large areas. Geographic information systems (GIS) assist in the display and manipulation of spatial data—points, lines, or areas with associated labels or data values. GIS is widely used by public agencies and private firms that have large land holdings or spatially distributed operations.