The Natural Area Coding System (NACS) is a global georeferencing system used to produce compact location codes requiring only 8 or 10 characters to specify a single address—a length similar to postal codes. As location-based services become more popular and the world becomes globalized, being able to efficiently, reliably, and universally specify locations is important. NACS codes can be easily used by consumers, GIS professionals, and computers alongside other geographic references, including geodetic datums, geographic coordinates, geographic area codes, map grids, addresses, postal codes, and property identifiers throughout the world. This entry introduces the NACS and outlines some of its important uses.