In this chapter, you learned a lot about geographic coordinate systems, projected coordinate systems, and the pieces that make up these systems. You learned the basic principles of choosing a projection for your data and map. While it may not have felt like it, this chapter only scratched the surface of coordinate systems. Understanding and correctly applying geographic coordinate systems and projected coordinate systems will set you apart from novice GIS users. Coordinate systems are probably the most important portion of GIS, because no matter how good your map or analysis looks, if the spatial data used in that analysis has the wrong geographic coordinate system or projected coordinate system, then your data is wrong. Having the wrong projection can cost a project a lot of time and money when the real world doesn't match up with the data and map you created.
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