MapTools Knowledge Base
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“What does WGS84 mean?”
WGS 84 (World Geodetic System 1984) is a global datum — a mathematical model of Earth's shape plus a reference frame for measuring coordinates.
Before satellites, surveyors used separate regional datums (like NAD 27 for North America) because each was designed as the best fit for its part of the world. Once we could measure Earth from space, a single datum could be defined to fit the entire planet. WGS 84 is that datum: its ellipsoid is a best fit for the whole Earth, and its reference frame is anchored to Earth's center of mass rather than to a ground station in one country.
WGS 84 is what every GPS satellite emits coordinates against. When you see a coordinate without an explicit datum label, WGS 84 is usually the default assumption in modern practice — though the datum is still an important part of the coordinate, even if it's not written out.