Lines of latitude measure the distance north or south of the equator. They are imaginary reference lines that circle the Earth parallel to the equator and run east to west. The equator is the most well-known parallel and is valued at zero degrees. Latitude is measured in degrees, minutes, and seconds north or south, with the north and south poles as 90 degrees north and south, respectively. Latitude combined with longitude gives a coordinate for any location on the Earth. Latitude lines are used to determine how far up or down on the Earth a location is. Latitude measurements can be written in several ways, such as degrees, minutes, and seconds, or with decimals.