Birth rate, death rate and migration are the three major components of
population growth.
(i) Birth rate is the major component of growth because if birth rate is higher than death rate, growth rate will automatically increase.
(ii) Another major component is death rate. These days we find that there are improved health facilities and there is awareness among people about their health maintenance. With the result, death rate has declined leading to growth rate of the population.
(iii) Migration is another component of population growth. Though internal migration does not change the population of the country but it does affect the distribution of population within the country. International migration definitely changes the size of the population.

Density of population is calculated as the number-of persons per unit area. The population density of India in 2001 was 324 persons per sq. km.
(i) Regions with sparse population density: Rugged terrain and unfavourable climatic conditions are primarily responsible for sparse population in these areas. For example, Jammu and Kashmir, Arunachal Pradesh and Mizoram.
(ii) Regions with moderate population density: Hilly, dissected and rocky nature of terrain, moderate to low rainfall, shallow and less fertile soils hate influenced the population densities in these areas. For example, Assam and peninsular states.
(iii) Regions with high density of population: These areas have high population density because of the flat plains with fertile soils and abundant rainfall. For example, Northern plains and Kerala.