Longitudes are imaginary lines running North-South at right angles to the parallels and passing through poles known as lines of meridians. Longitudes are angular distances measured in degrees east or west of the Greenwich meridian, which runs North-South.
It extends between 180Β°W and 180Β°E and can be used in calculating local time. The lines of longitudes passing through Greenwich meridian are OΒ°, and are called prime meridian.