Geocentric Datum

A geocentric datum is a geodetic reference frame whose origin is the Earth’s center of mass, so positions are defined in an Earth-centered, Earth-fixed coordinate system rather than fitted to a local region. WGS 84 is the canonical example, the datum of GPS, with EPSG code 4326 for its geographic form. Geocentric datums suit satellite positioning because the orbit dynamics are referenced to the geocenter, and they let global data align without the offsets that local datums such as ED50 or OSGB36 carry. Charts increasingly use geocentric WGS 84 so GNSS fixes plot without a datum shift.