Definition

Latitude lines, also known as parallels, run horizontally around the Earth and measure the distance north or south of the equator. The equator, which circles the Earth midway between the North and South Poles, is designated as 0 degrees latitude. Latitude values north of the equator are positive, while those south of the equator are negative. The range of latitude extends from -90 degrees (the South Pole) to +90 degrees (the North Pole). Longitude lines, also called meridians, run vertically from the North Pole to the South Pole. The Prime Meridian, which passes through Greenwich, London, is designated as 0 degrees longitude. Longitude values to the east of the Prime Meridian are positive, while those to the west are negative. The range of longitude extends from -180 degrees (180 degrees west) to +180 degrees (180 degrees east).