Monaco is the most densely populated country of the world.

1. According to the 2001 census data reveals that Uttar Pradesh with a population size of 166 million.
2. It accounts for nearly 16% of the country's population.

1. Human being are producers and consumers of earth's resources.
2. Therefore, it is important to know how many people are there in a country, where do they live, how and why their numbers are increasing and what are their characteristics.

Mumbai, Bangalore, Delhi, Chennai and Ahmedabad.

Processes of population change
There are three main processes of population change.
They are:
(i) Birth rates
(ii) Death rates and
(iii) Migration.
A. Natural increase of population is the difference between birth rates and death rates.
1. Birth rate is the number of live births per thousand persons in a year.
(i) It is a major component of growth in India because birth rates have always been higher than death rates here.
2. Death rate is the number of deaths per thousand persons in a year.
(ii) Main cause of rapid rate of growth of the Indian population is the fast decline in death rates.
3. Till 1980, high birth rates and declining death rates led to a large difference between birth rates and death rates.
(iii) It resulted in higher rates of population growth.
4. After 1981, birth rates have also started declining gradually. It has resulted in a gradual decline in the rate of population growth.
The reasons for this trend are:
(i) Most of the people especially in urban areas have adopted two children norms due to which birth rate declined.
(ii) Womenfolk are more conscious of their health.
(iii) Family welfare schemes are being adopted in a big way.
(iv) Muslim population has also started to keep the family small.
B. Migration is the third component of population growth.
(i) It is the movement of people across regions and territories.
(ii) It is both internal and international. 
(iii) Internal migration is the movement of people from one region to another within the country.
(iv) International migration is the movement of people from one to another country. 
Internal migration does not change the size of the population but influences the distribution of population within the country.

Census
(i) A census is an official enumeration of population done periodically.
(ii) In India the first census was held in the year 1872.
(iii) Since then censuses have been held regularly every ten years.
(iv) The Indian census is the most comprehensive source of demographic, social and economic data.
(v) The decennial census of India is the largest single administrative exercise of its kind in the world.
Information we get from census are:
(i) Population size and distribution
(ii) Population growth and processes of population change
(iii) Characteristics or qualities of the population.

Following are most densely populated areas of India:
(i) West Bengal
(ii) Kerala
(iii) Uttar Pradesh and Bihar
(iv) Punjab
(v) Haryana
The main reason behind this density of population is smooth plain, fertile areas and sufficient and regular supply of water. Moreover, rice or wheat is grown in these areas. Hence, there are food supplies for maximum people.

(a) The least populous state of India is Sikkim.
(b) These areas are very sparsely populated due to
1. hilly terrain
2. heavy rainfall
3. thick forests.

1. Population size and distribution: How many people are there and where they reside.
2. Population growth and processes of population change: How the population has grown and change through time.
3. Characteristics or qualities of population: Their age, sex composition, literacy level, occupational structures and health conditions.