Understanding coordinate systems

There are two types of coordinate systems: geographic and projected. A geographic coordinate system is used to locate objects on the curved surface of the earth. A projected coordinate system is used to locate objects on a flat surface—a paper map or a digital map displayed on a flat computer screen.

Each of these coordinate systems attempts to model the earth and feature locations accurately, but, as you will learn, no system is completely accurate. In this topic, you will learn the basics of how geographic and projected coordinate systems work.