Demography is the study of human populations . Births, deaths and migration are the ‘big three’ of demography, jointly producing population stability or change.Demography is the statistical study of living populations. It can be a very general science that can be applied to any kind of dynamic living population, i.e., one that changes over time or space (see population dynamics). It encompasses the study of the size, structure, and distribution of these populations, and spatial and/or temporal changes in them in response to birth, migration, aging and death. For etymology(origins) of demography.