Demography: This is the study of populations. In the other words demography is the statistical study of human population. This may be a very general science which can be applied to any type of dynamic human population, whether that one changes over time or space like population dynamics. Demography encompasses the study of the structure, size or distribution of these populations, and some temporal changes in them in response to birth, aging, migration or death.
Demographic can analysis to whole societies & groups defined by criteria like as nationality, education, ethnicity or religion. Institutionally we can say that demography is usually considered a field of sociology, though the number of independent demography departments. The term demographics is sometimes used erroneously for demography.