what is wgs84

WGS84 stands for World Geodetic System 1984, which is a standard used in cartography, geodesy, and satellite navigation including GPS. It defines an Earth-centered, Earth-fixed coordinate system and a geodetic datum, and also describes the reference ellipsoid, a standard coordinate system, altitude data, and a geoid. The WGS84 coordinate system is used as a reference coordinate system for the Global Positioning System (GPS) . It is geocentric and globally consistent within 1 m, and is based on a consistent set of constants and model parameters that describe the Earths size, shape, and gravity and geomagnetic fields. WGS84 is defined and maintained by the United States National Geospatial-Intelligence Agency (NGA) and is consistent, to about 1cm, with the International Terrestrial Reference Frame (ITRF) . It is important to note that there are multiple realizations of WGS84, and for highly-accurate coordinates, it is important to know which realization the coordinates are referenced to.