In geography, a hemisphere is one of the equal halves of a sphere, and when applied to Earth, it refers to half of the planet. The Earth is divided into four hemispheres by two imaginary dividing lines, the equator and the prime meridian. The four hemispheres are:

• Northern Hemisphere: The half of the Earth that is north of the equator. It includes North America, Central America, Europe, mainland Asia, about half of Africa, and a small part of South America.

• Southern Hemisphere: The half of the Earth that is south of the equator. It includes most of South America, all of Australia, all of Antarctica, and about half of Africa.

• Eastern Hemisphere: The half of the Earth that is east of the prime meridian and west of the 180th meridian. It includes most of Africa, Europe, Asia, and Australia, as well as the Indian and Western Pacific Oceans.

• Western Hemisphere: The half of the Earth that is west of the prime meridian and east of the 180th meridian. It includes North and South America, the eastern Pacific Ocean, the Caribbean Sea, and the majority of the Atlantic Ocean.

Hemispheres can also be divided geographically, culturally, religiously, or based on prominent geographic features. Understanding these divisions is essential for studying Earths geographic distribution, cultural differences, and the prominence of various geographic features.