Lines of longitude are measured in degrees east or west of the prime meridian, which runs through Greenwich in London, while lines of latitude are given in degrees north of south of the equator.

• 穿过伦敦格林尼治的经线叫做本初子午线（0度经线），经度以东西距离这条经线多少度来计算，而纬度以离赤道南北多少度来计算。