The world population is the total number of humans alive on the planet Earth at a given time. According to estimates published by the United States Census Bureau, the Earth’s population reached 7.5 billion in April 2017. The United Nations estimates it will further increase to 11.2 billion in the year 2100.
In line with population projections, this figure continues to grow at rates that are unprecedented prior to the 20th century. Approximately one fifth of all humans that have existed in the last six thousand years are currently alive. By some estimates, there are now one billion (thousand million) people in the world between the ages of fifteen and twenty-four.