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.

Large scale industries were established due to the advancing technology and the country became industrialised. New cities emerged around those industries. First small settlements cropped up around these industries, then markets and shops were opened to provide the people with essential commodities. Then hotels, schools, colleges, offices, companies, etc. were set up for the people. In this way, gradually cities were developed and urbanisation took place. In this way, we can say that technology plays a great role in the process of urbanisation.

The disadvantages of Green Revolution were:

1. This revolution created stark contrast between poor peasants and the landlords produced conditions favourable for leftwing organisations to organise the poor peasants. Discrimination and exploitation of poor farmers by the landlords became a wide set practice.
2. This revolution also resulted in the rise of middleman peasants sections. These were farmers with medium size holdings, who benefited from the changes and soon emerged politically influential in many parts of the country.

Annual Growth Rate The rate at which the number of individuals in a population increase in 1 year as a fraction of the initial population is called an annual growth rate of population.
The annual growth rate is affected by the birth rate in the following ways:

1. With the increase in birth rate, the annual growth rate generally increases.
2. For a larger population, even having a lower birth rate, the annual growth rate keeps on increasing.
3. For example, since 1981 the birth rates declined rapidly, still 18.20 crore people were added to the total population in the 1990s alone. If we calculate the annual growth rate based on these data it becomes very high.

The two principles to understand the theoretical interpretation of caste are hierarchy and discrimination.  

Explanation:  

• The Indian societal system used to be divided into small groups based on their traditional occupation of varnas. These occupations were placed in a hierarchical fashion and created the basis of the caste system.  
• The second principle that guided this system into place is the aspect of discrimination. The upper classes discriminated against the lower castes based on their varnas and made them do the menial tasks of the society.
• The lower castes were subjected to centuries of conditioning and accepted this as their fate without questioning.

1. Increasing inter regional, economic and infrastructural inequalities.
2. The states are not developed in some uniform manner, some are well developed while some to receive attention. This creates discord among the citizens and a feeling of alievation.
3. The market economy tends to increase the gap between developed and backward classes. The rich tend to get richer while the poor tend to get poorer.

1. Sanskritisation process promoted the sacred outlook; while Westernisation process promoted secular outlook.
2. Sanskritisation is a process of upward mobility by a process of imitation while Westernisation is a process of upward mobility by a process of development.
3. Sanskritisation implies mobility within the framework of caste while Westernisation implies mobility outside the framework of caste.
4. While Sanskritisation puts a taboo on meat-eating and consumption of alcohol, Westernisation promoted meat-eating and consumption of alcohol.