While the use of GPS technology is growing dramatically among land surveyors there is not a commensurate growth in the understanding of coordinate systems. It is not possible to survey accurately or use GPS properly without taking the shape of the earth into consideration and without a clear understanding of coordinate systems. And there is little grasp of these principles in the professional GIS community. Jan van Sickle's new text covers ellipsoids, datums and plane coordinate systems as they are used in GIS and GPS. It also covers the geoid and the concepts of elevation. Each of these topics implies other issues from mapping angles to datum design. These ideas are complex, yet they are presented as a logical progression of ideas and in a manner which is neither too complicated nor oversimplified, avoiding getting bogged down in the mathematics.