What divides the Earth into the Northern and the Southern Hemispheres?

What divides the Earth into the Northern and the Southern Hemispheres?

زمین کو شمالی اور جنوبی نصف کرہ میں کون تقسیم کرتا ہے؟
Explanation
The Equator is an imaginary line that divides the Earth into the Northern and Southern Hemispheres.
It lies at 0° latitude.
It is equidistant from the North and South Poles.