Geographers also divide the globe along imaginary vertical lines called meridians of longitude, which are measured in degrees (°). The longitude line called the Prime Meridian runs from pole to pole through Greenwich, England. All meridians of longitude come together at the North and South Poles.
Together, the pattern of parallels of latitude and meridians of longitude is called the global grid. Using the lines of latitude and longitude, you can locate any place on Earth. For example, the location of 30° north latitude and 90° west longitude is usually written as 30° N, 90° W. Only one place on Earth has these coordinates—the city of New Orleans, in the state of Louisiana.
▴ Compass
Wherever you are on Earth, a compass can be used to show direction.