: Both rates are low; the population stabilizes.
: Birth rates begin to fall as society urbanizes and education (especially for women) increases. Demography: The Study of Human Population
: The movement of people across borders. While net migration is zero at a global level, it is a critical driver of "fast demography" at the national level, often offsetting natural population declines in developed countries. The Demographic Transition Model (DTM) : Both rates are low; the population stabilizes
: The incidence of death in a population. Improvements in healthcare and nutrition have led to a significant increase in global life expectancy, which rose by over eight years between 1995 and 2026. While net migration is zero at a global
Most modern demographic analysis is framed by the , which describes the historical shift from high birth and death rates to low ones as societies develop.
: The actual reproductive performance of a population. Demographers measure this through the Total Fertility Rate (TFR) —the average number of children a woman would have in her lifetime. Currently, the world is nearing the "replacement level" of 2.1, below which a population eventually begins to shrink.