what is a datum used for
This confuses many people. In simple terms: A datum is a system which allows the location of latitudes and longitudes (and heights) to be identified onto the surface of the Earth-ie onto the surface of a âroundâ object.
Other nations' maps often use coordinates computed assuming the Earth is a completely different size and shape from what the Department of Defense uses, but we have to be ready to fight around the world. US forces now use a datum called World Geodetic System 1984, or WGS 84. The National Imagery and Mapping Agency (NGA) produces all of its new maps with this system. Unfortunately, we reprint many of our maps from products made by allied countries that use local datums.