A meridian is an imaginary line that runs across the surface of the Earth from the North Pole to the South Pole. These meridians are used to measure the geographic longitude of a location and establish its position on the planet.
The reference meridian, called the Prime Meridian or Greenwich Meridian, divides the Earth into two hemispheres: East and West. Each meridian is assigned a numerical value in degrees, ranging from 0° at the Prime Meridian to 180° at the Opposite Meridian.
Meridians are fundamental for navigation, cartography, and the precise determination of time in different zones of the world.
