About seven billion people live on Earth. They live in about 200 different lands called countries. Some, for example, Russia, are large with many large cities. Others, for example, Vatican City, are small. The five countries with the most people are China, India, the United States, Indonesia, and Brazil. About 90% of people live in the north half of the world, which has most of the land. Scientists think that people originally came from Africa. Now, 70% of all people do not live in Africa but in Europe and Asia.