Latitude and Longitude
Latitude and longitude are the angular coordinates used to describe positions on Earth, giving every place a north-south and east-west address.
What the grid does
Latitude and longitude form a global reference grid. Instead of describing a place by nearby landmarks, the grid names its position with two angular measurements. That makes it possible to record locations for maps, navigation, surveying, weather observations, emergency response, and digital geospatial data.
Latitude: north and south
Latitude is measured from the equator, which is 0 degrees latitude. Values increase toward 90 degrees north at the North Pole and 90 degrees south at the South Pole. Lines of latitude, also called parallels, circle Earth east-west and stay roughly parallel to one another.
Longitude: east and west
Longitude is measured from a starting meridian. The historical prime meridian runs through Greenwich, England, and marks 0 degrees longitude; the antimeridian lies opposite it at 180 degrees. Lines of longitude, or meridians, run from pole to pole and meet at the poles.
How coordinates are written
A coordinate pair usually lists latitude first and longitude second. Decimal degrees are common in software, while degrees-minutes-seconds remain common on charts, signs, and educational maps. North and east can be written as positive values, while south and west are often written as negative values in digital systems.
Distance and scale
One degree of latitude is about 111 kilometers on Earth's surface. Longitude spacing changes with latitude: meridians are farthest apart at the equator and converge to zero distance at the poles. That is why a coordinate change of one degree longitude covers very different ground distances in Ecuador, Canada, and Antarctica.
Datums and precision
Latitude and longitude are not complete unless the reference frame is understood. A horizontal datum defines the model and control points used to anchor coordinates to Earth. Modern GPS, national mapping systems, and survey networks use datums and reference frames so coordinates remain consistent across instruments and datasets.
Why it matters
Latitude and longitude are the shared language behind addresses on maps, GPS coordinates, aircraft routes, ocean charts, scientific observations, and location-tagged data. When coordinates are precise and documented, people can return to the same place, combine datasets, and make spatial decisions with less ambiguity.