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Latitude and longitude are the universal coordinate system that precisely identifies any point on Earth. Although modern GPS and smartphone maps hide the raw numbers behind user‑friendly maps, the underlying grid remains essential for accurate navigation, scientific research, and global communication.
In this system the planet is sliced into a network of parallel lines (latitudes) and meridians (longitudes). Latitude lines run horizontally, parallel to the equator, which is set at 0° and serves as the baseline. Moving north or south from the equator, each line increases by one degree until the poles at 90° N and 90° S. Everything north of the equator falls within the Northern Hemisphere, and everything south lies in the Southern Hemisphere.
Meridians are the vertical lines of longitude. Their reference point is the Prime Meridian (0°), which cuts through Greenwich, England—a location selected in 1884 to standardize global coordinates. The meridian directly opposite, 180° east or west, is the antipodal line. East of Greenwich is the Eastern Hemisphere; west of it, the Western Hemisphere. Like latitude, longitude is measured in degrees, increasing one degree for each step east or west from the Prime Meridian.
Reading coordinates mirrors reading a clock: you start with the major unit and refine the precision with smaller increments. A full coordinate is expressed in degrees, minutes, and seconds (DMS). One degree spans roughly 69 miles (111 km) at the equator. Each degree is subdivided into 60 minutes, and each minute into 60 seconds, allowing pinpoint accuracy to a few feet when expressed to several decimal places.
For example, Wrigley Field in Chicago is located at 41° 56' 54.3732" N latitude and 87° 39' 19.2024" W longitude. The first part, 41° 56' 54.3732" N, tells you the latitude: 41 degrees, 56 minutes, and 54.3732 seconds north of the equator. The second part, 87° 39' 19.2024" W, gives the longitude: 87 degrees, 39 minutes, and 19.2024 seconds west of the Prime Meridian.
By visualizing these numbers on a globe or a detailed map, you can locate Wrigley Field—or any other point—exactly where it lies on the Earth’s surface.
