The population density of a region is measured by counting the number of people that live per each square kilometer of surface area in the region. The average population densities of nations do not reveal the population densities of different regions accurately. This is due to the fact that population density varies greatly between different areas. 

For example, the average population density of Egypt is 82 inhabitants per square meter. However, the Nile valley alone has a population density of over a thousand people per square kilometer. This population density is significantly lowered by the desert areas of Egypt, which are largely uninhabited.

Image on the right: The satellite image shows how habitation is centered along the river Nile in Egypt.

The Earth has plenty of space for humans, but the conditions for permanent inhabitation vary greatly between different areas. Over one third (40%) of Earth's land surface area is uninhabitable. These uninhabitable areas consist of frigid polar regions and Antarctica, deserts, high mountain ranges, and thick rainforests.

Approximately 80 % of Earth's population lives at elevations below 500 meters. Earth's population is concentrated on the shores of bodies of water, such as seas, rivers and lakes. The majority of the planet's population is based in the northern hemisphere.

Click the picture three times to expand it! Describe the population distribution on planet Earth.​