Demography is the science that studies the population and the changes that occur in it.
The study of population is carried out by finding out the population, the processes of movement (migration) and the natural movement of the population. The latter is a major factor in the ever-changing population. Natural population growth, determined by the difference between fertility and mortality, is an indicator that mainly characterizes the changes in the population.
The population size is determined periodically by population censuses (see), which give an accurate picture of the population at the time of the census, its composition by gender, age, nationality, degree of education, etc. including in the field of cultural construction.
Of great importance are changes in the size and composition of the population as a result of migration processes. A feature of these processes in the USSR is their planned nature, which excludes spontaneity, which gives rise to an unfavorable sanitary condition of the population.
The most important section of demography is the study of reproduction, the natural movement of the population - the processes of fertility (see), infant and total mortality (see). These processes not only reflect changes in the size and composition of the population, but are also of great importance for assessing the health status of the population . Especially important in this regard are the mortality rates of children under the age of 1 year (see Infant mortality).
See also t. 3, table, section " Health ".