The basic factors affecting the population of India are as under:

(i) Birth Rate: It is the number of births per 1000 individuals of a population per annum. It increases both population size and population density. According to the 2001 Census, the birth rate of the Indian population was 26 per 1000.

(ii) Death or Mortality Rate: It is expressed as the number of deaths per 1,000 individuals of a population per year. It decreases both population size and population density. According to the 2001 Census, the death rate of the Indian population was 8 per 1000 persons.

(iii) Immigration: It is the entry of more individuals into a local population of a species in a specific area from outside due to more favorable conditions in that area. It increases the population size of that area Eg. Immigration of many persons from various states into Delhi.

(iv) Emigration: It is the departure of some individuals from a local population of a specific area to another area due to unfavorable conditions in the former. It decreases the population size of that area Eg. Emigration of many Indians to Arab countries.

(v) Environmental resistance: It is the sum of all the inhibitory factors which prevent the biotic potential to be realized so it does not allow a population to soar towards infinity. It includes various harmful environmental factors like scarcity of food and shelter, natural calamities like tsunami, floods etc, and certain biotic factors like pathogens, parasites and predators.