This lesson covers the topics of geodesy, datums, map projections, and map coordinate systems. Geodesy addresses the shape of the earth: the topographic surface, geoid, and best-fit ellipsoid. Datums addresses the position and orientation or the best-fit ellipsoid and the resulting coordinates. Map projections addresses the different ways to project an ellipsoidal datum onto a flat surface. Each projection has unique properties and each has pros and cons. Coordinate systems addresses the different ways that a rectangular coordinate system can be superposed on latitude-longitude graticule.