Final answer:
The equator is the significant line that divides the Earth into the Northern and Southern Hemispheres, and is defined as 0 degrees latitude.
Step-by-step explanation:
The important line that breaks the World up into the Northern and Southern Hemispheres is the equator. The equator is the largest circle of latitude on Earth and is designated as 0 degrees latitude. Geographically, it serves as an imaginary line that dissects the Earth into two equal halves: the Northern Hemisphere and the Southern Hemisphere.
Geographers and cartographers utilize the equator, along with the prime meridian, to organize locations on Earth into a grid system comprised of lines of latitude and longitude, enabling precise pinpointing of any location.
The equator is significant for several reasons, including the fact that it is the point at which the Earth's surface receives the most direct sunlight during the equinoxes, resulting in equal day and night durations across the globe.