Why are lines of latitude also called parallels?

Lines of latitude are also called parallels because they run horizontally to each other and the equator. They are spaced evenly apart and are always parallel to each other. Parallel means that a line is equal from another and will never intersect with each other. In contrast, longitude lines run vertically from the North and South Pole so they are not of equal distance or parallel to each other. The distance between the lines vary as they curve to accommodate the roundness of the Earth.