equator

Intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and midway between the poles

The Earth's equator is an imaginary planetary line that is about 40,075 km (24,901 mi) long in circumference. The equator divides the planet into the Northern Hemisphere and Southern Hemisphere and is located at 0 degrees latitude, the halfway line between the North Pole and South Pole.