Textbook for the South African student Demography is the scientific study of the size, composition and change in human population. It studies empirical phenomena and describes them as precisely as possible. However, to understand this definition better, each of its key concepts requires attention. Demographic terminology is currently also used to describe certain phenomena relating to insect and animal populations. Demography, however, is in the first place a discipline that studies human populations. The descriptions, analyses and explanations in this textbook therefore refer to human populations only.