What is the imaginary line which divides the Earth's globe into northern and southern hemispheres called?

Earth's Equator is a specific case of a planetary equator. It is about 40,075 km (24,901 mi) long, of which 78.8% lies across water and 21.3% over land.

In spatial (3D) geometry, as applied in astronomy, the equator of a rotating spheroid (such as a planet) is the parallel (circle of latitude) at which latitude is defined to be 0°. It is the imaginary line on the spheroid, equidistant from its poles, dividing it into northern and southern hemispheres.

When the Sun is directly above the Earth's Equator (on the equinoxes of approximately March 20 and September 23), sunlight shines perpendicular to the Earth's axis of rotation, and all latitudes have a 12-hour day and 12-hour night. On and near the Equator sunlight comes from almost directly above every day year-round, and thus the Equator has a rather stable daytime temperature the whole year.