# Geographic coordinate systems |  | The **Geographic coordinate system** (GCS) is a spherical or geodetic coordinate system for measuring and communicating positions directly on the Earth as latitude and longitude. It is the simplest, oldest and most widely used of the various spatial reference systems that are in use, and forms the basis for most others. Although latitude and longitude form a coordinate tuple like a cartesian coordinate system, the geographic coordinate system is not cartesian because the measurements are angles and are not on a planar surface. | |-|-| | | wikipedia:: [Geographic coordinate system](https://en.wikipedia.org/wiki/Geographic_coordinate_system) | Traditional GCS: E.g: [[Kansas City]] City Hall: `39.10035° N, 94.57792° W` ## Decimal Degrees [Decimal degrees](https://en.wikipedia.org/wiki/Decimal_degrees) What many digital mapping, [[GIS]], [[Tech]] systems use. > Positive latitudes are north of the equator, negative latitudes are south of the equator. Positive longitudes are east of the Prime Meridian; negative longitudes are west of the Prime Meridian. Latitude and longitude are usually expressed in that sequence, latitude before longitude. The abbreviation dLL has been used in the scientific literature with locations in texts being identified as a tuple within square brackets, for example [54.579806, 3.582]. The appropriate decimal places are used,[1] negative values are given as hyphen-minus, Unicode 002D. US Capitol: `38.8897,-77.0089` https://www.openstreetmap.org/?mlat=38.8897&mlon=-77.0089#map=19/38.8897/-77.0089 ## ISO 6709 [ISO 6709](https://en.wikipedia.org/wiki/ISO_6709) `50°40′46.461″N 95°48′26.533″W 123.45m` ## [[Geo URI scheme]] `geo:25.245470718844146,51.45400942457904`