The world population has grown very rapidly because the death rate has
gone down as a result of the growth of food supplies and the improvement
of medical facilities.
Also, unlike the death rate, the birth rate has
remained quite high.
The birth rate and the death rate are two factors that influence
population change.
The birth rate is the number of live births per 1000
people while the death rate is the number of deaths per 1000 people.
Thus, the birth and death
rates affect the balance of population.