Coordinates are integral building tools for GIS, cartography, surveying and are vital to the many applications we use today such as smart phones, car navigation systems and driverless cars. Basic GIS Coordinates, Third Edition grants readers with a solid understanding of coordinates and coordinate systems and how they operate as well as valuable insight into what causes them to malfunction. This practical and comprehensive guide lays out the foundation of a coordinate system and the implications behind building it as it elaborates on heights, two coordinate systems, and the rectangular system.The previous editions described horizontal and vertical datums such as the North American Datum 1983 (NAD 83) and the North American Vertical Datum 1988 (NAVD 88). Both will be replaced in 2022 or thereabouts. The National Geodetic Survey (NGS) plans to replace NAD83 with a new semi-dynamic terrestrial reference frame for North America and a new vertical datum will replace NAVD88. The foundation of the new vertical datum will be a temporally tracked gravimetric geoid. The interim period is intended to smooth the transition to the new paradigm and this new edition explores the changes and provides assistance in understanding them.