Coordinate reference system. The combination of a geographic and projected coordinate systems that define how two-dimensional maps relate to locations on the earth’s surface. Geographic coordinate systems use a three-dimensional spherical surface to define those locations, referencing points on that surface through angles (latitude and longitude values) measured from the earth’s center. Projected coordinate systems are based on flat two-dimensional surfaces, with locations referenced by x, y coordinates measured as constant lengths and distances across that surface. See also SRID and SRS.
ORIGIN: OSGeo Glossary (last updated: 2019-10-29)