when was the need to study …

The word ‘Demography’ is a combination of two Greek words, ‘Demos’ meaning people and ‘Graphy’ meaning science. Thus demography is the science of people. Demography is the statistical and mathematical study of the size, composition, and spatial distribution of human populations and how these features change over time. Data are obtained from a census of the population and from registries: records of events like birth, deaths, migrations, marriages, divorces, diseases, and employment.
Importance of Demography:

• For the Economy: It helps to understand the growth rate of the economy and the growth rate of the population. If the population is increasing at a faster rate, the pace of development of the economy will be slow. In such a case, the government has to undertake corrective measures to control the growth of population and to accelerate the development of the economy. Rapid population growth reduces per capita income, lowers the standard of living, resulting in mass unemployment and underemployment. It may cause environmental damage and puts an extra burden on existing social infrastructure. Hence we can conclude that the study of demography is very important to an economy.
• For Economic Planning: Data relating to the present trend in population growth help the planners in formulating policies for the economic plan of the country for the future. Considering the population growth rate targets of agricultural and industrial products, of social and basic services like schools and other educational institutions, hospitals, houses, electricity, transport, etc. are fixed. In case of high population growth rate, it is used in formulating a policy to control the birth rate.
• For Society: Rapid population growth reduces per capita income, lowers the standard of living, resulting in mass unemployment and underemployment. It puts stress on basic services like water, electricity, transport and communications, public health, education, etc. It may also result in migration and unplanned urbanization which further lead to unavailability of civic amenities and the law and order problem. Hence to have a check on this problem, there is a necessity of the study of demography.
• For Administrators / Government: In under-developed countries, almost all social and economic problems are associated with the growth of population. The government has to tackle and find solutions to the problems arising from the growth of population. Rapid population growth leads to unplanned urbanization which further leads to problems like coming up of shanty towns, pollution, drainage, water, electricity, transport, etc. in cities.
• For Political System: The information obtained through the study of demography is used by the election commission to the demarcation of constituencies. It also gives information about the increase and decrease in the number of voters. Political parties can frame their policies and election manifestos at the time of elections.