WGS84 – World Geodetic System 1984

WGS84 is a global reference coordinate system used notably by GPS. It defines Earth’s shape (ellipsoid), origin, orientation, and time‐dependent reference frame for positioning. The accuracy of WGS84 depends on the realization: early versions provided ~1-2 m absolute accuracy; newer realizations (such as G2139) are aligned with ITRF2020 and can provide sub-decimetre to centimetre consistency with ITRF under favourable conditions.