The population change refers to change of number people during a specific time. the world population has not been stable. It has increased. This is actually due to changes in the number of births and deaths. For an extremely long period of history , until the 1800s, the world's population grew steady but slowly. Large number of babies were born, but they died early too. This was as there were no proper health facilities. The population increase in the world is mainly due to rapid increase in natural growth rate which means population increased year by year.