Demography is the scientific study of human population.
Focus of Demography :
Demography focuses its attention on three readily observable human phenomena :
(i) Changes in population ‘size’ (growth or decline).
(ii) The ‘composition’ of the population and
(iii) the ‘distribution’ of population in space.
Demographic Cycle (transition)
The history of world population since 1950 suggests that there is a demographic cycle of 5 stages through which a nation passes :
(I) First stage - high stationary.
(ii) Second stage - early expanding .
(iii) Third stage - late expanding.
(iv) Fourth stage - law stationary.
(v) Fifth stage- declining.
Population Explosion :
“Population explosion” means a rate more than a very rapid growth of population.
There is no definite bench mark, it must be in relation to the resources of a particular country. Opinion varies, some say it begins when growth crosses 2%, others say it is when the growth reaches the rate of 2.5%.
Population Pyramid :
The age of people of Bangladesh is typical of developing countries, with a broad base and a tapering top, age group. This also indicates a rapid population growth in future.