When and why did the world population grow? And how does rapid population growth come to an end? These are the big questions that are central to this research article. The world population increased from 1 billion in 1800 to 7.7 billion today. The world population growth rate has halved from above 2% per year 50 years ago to 1.05% per year. Other relevant research: World population growth – This article is focusing on the history of population growth up to the present. We show how the world population grew over the last several thousand years and we explain what has been driving this change. Life expectancy – Improving health leads to falling mortality and is therefore the factor that increases the size of the population. Life expectancy, which measures the age of death, has doubled in every region in the world as we show here. Child & infant mortality – Mortality at a young age has a particularly big impact on demographic change. Fertility rates – Rapid population growth has been a temporary phenomenon in many countries. It comes to an end when the average number of births per woman – the fertility rate – declines. In the article we show the data and explain why fertility rates declined. Age Structure – What is the age profile of populations around the world? How did it change and what will the age structure of populations look like in the future?