The imaginarly line at 0º latitude which divides the earth into two equal parts is called Equator. The Equator divides the earth into Northern and Southern Hemisphere.
Prime Meridian divides the earth into the Eastern and Western Hemispheres. Prime Meridian is a line of longitude, at which longitude is defined to be 0°.
The Western Hemisphere includes Greenland , about half of Antarctica, and all of North and South America which includes the Caribbean and Central America.
Eastern Hemisphere includes most of Africa, most of Europe, about half of Antarctica and all of Asia and Australia/Oceania.
The Northern Hemisphere includes all of North America, the northern portion of South America, Eurpoe, about two-thirds of Africa, mostly all of Asia.
The Southern Hemisphere includes Antartica, Australia/Oceania, most of South America and one-third of Africa.