People, Cities and Maps of the World

More than 8 billion people live on Earth, but we are not spread evenly across it. Most people live in areas with mild climates, good soil, and access to fresh water. Very few live in deserts, high mountains, or polar regions. More than half the world's population now lives in urban areas — towns and cities — and that share is growing every single year.

The study of human populations — how many people there are, where they live, and how this changes over time — is called demography. The total number of people on Earth has grown extremely fast in the last two hundred years, thanks to better food, cleaner water, and medicine that helps people live longer. In the year 1800 there were about one billion people; today there are more than eight times as many.

Cities tend to grow at natural crossroads: near rivers, harbours, fertile plains, or at trade routes. London grew around the Thames because the river provided fresh water, a way to travel, and a harbour for trade. New York grew on a natural harbour between the Hudson and East rivers. The geography of a place often explains exactly why a great city sprang up there and not somewhere else.