A GCP is a ground control point. Ground control points are necessary to reference or "tie together" remotely sensed imagery and data to specific locations on earth. In this way, images and data captured from drones, aircraft, and satellites can be accurately mapped to specific ground locations within a GIS or CAD program. This helps to ensure that multiple datasets all accurately match up with each other. The process of mapping a dataset to exact ground locations is called orthorectification. Using Ground control points are necessary for to make data usable by governments, designers, engineers, and private companies.Ground control points are usually created by land surveyors who take the time to go the location and accurately survey the latitude, longitude and elevation of the specific control point.