India has the second largest population in the world with over 1.21 billion people according to the 2011 census. It is projected to surpass China as the world's most populous country by 2025. India's population growth rate is 1.41% and over half of Indians are under 25 years old. A census systematically collects and records information about members of a population and occurs regularly to count a particular population.

3.  A population is a summation of all the organisms of the same group
or species, who live in the same geographical area, and have the capability of
interbreeding.[1][2] In ecology the population of a certain species in a certain area is
estimated using the Lincoln Index. The area that is used to define
a sexual population is defined as the area where inter-breeding is potentially possible
between any pair within the area. The probability of interbreeding is greater than
the probability of cross-breeding with individuals from other areas. Under normal
conditions, breeding is substantially more common within the area than across the
border.[3]

4.  The demographics of India are inclusive of the second most populous country in
the world, with over 1.21 billion people (2011 census), more than a sixth of the world's
population. Already containing 17.5% of the world's population, India is projected to be
the world's most populous country by 2025, surpassing China, its population reaching 1.6
billion by 2050.[4][5] Its population growth rate is 1.41%, ranking 102nd in the world in
2010.[6] Indian population reached the billion mark in 2000.
 India has more than 50% of its population below the age of 25 and more than 65%
below the age of 35. It is expected that, in 2020, the average age of an Indian will be 29
years, compared to 37 for China and 48 for Japan; and, by 2030, India's dependency
ratio should be just over 0.4.[7]

5.  : The average annual percent change in the population, resulting from
a surplus (or deficit) of births over deaths and the balance of migrants
entering and leaving a country. The rate may be positive or negative. The
growth rate is a factor in determining how great a burden would be
imposed on a country by the changing needs of its people for
infrastructure (e.g., schools, hospitals, housing, roads), resources (e.g.,
food, water, electricity), and jobs. Rapid population growth can be seen as
threatening by neighboring countries.

6.  A census is the procedure of systematically acquiring and
recording information about the members of a given population. It is a regularly
occurring and official count of a particular population. The term is used mostly in
connection with national population and housing censuses; other common censuses
include agriculture, business, and traffic censuses. The United Nations defines the
essential features of population and housing censuses as "individual enumeration,
universality within a defined territory, simultaneity and defined periodicity", and
recommends that population censuses be taken at least every 10 years. United Nations
recommendations also cover census topics to be collected, official definitions,
classifications and other useful information to coordinate international practice.