The period from 1901 to 1921 is considered a phase of stagnant or minimal population growth in India, as the growth rate was extremely low, even experiencing a negative growth rate between 1911 and 1921. Both birth and death rates were high, which kept the population increase at a low level. Factors such as poor healthcare and medical services, widespread illiteracy, and an inefficient distribution system for food and other essential needs were major contributors to the high birth and death rates during this time. The period from 1921 to 1951 is described as one of steady population growth, as overall improvements in health and sanitation reduced the mortality rate across the country. Simultaneously, better transportation and communication systems enhanced the distribution of resources. The crude birth rate remained high, leading to a higher growth rate compared to the previous period, despite the challenges posed by the Great Economic Depression in the 1920s and World War II. The years between 1951 and 1981 are referred to as the period of population explosion in India, which was driven by a rapid decline in the mortality rate while the fertility rate remained high. The average annual growth rate reached 2.2 percent. During this time, after India's independence, the introduction of developmental activities through a centralized planning process helped improve the economy and living conditions for a large segment of the population. This contributed to a higher natural increase and growth rate. Additionally, increased international migration, particularly from Tibet, Bangladesh, Nepal, and Pakistan, further boosted the population growth. From 1981 to the present, while the growth rate has remained high, it has gradually slowed down. This decrease is primarily attributed to a declining crude birth rate, which has been influenced by factors such as an increase in the average age at marriage and improvements in the quality of life, particularly in terms of female education across the country.