The population of India according to the 2011 Census was 1.324 billion.

Explanation:
The 2011 Census of India is the 15th national census conducted by the Government of India. It was conducted in two phases - the first phase was from April to September 2010 and the second phase was from February to March 2011. The data collected during this census provides valuable information about the population, demographics, and socio-economic characteristics of the country.

The 2011 Census revealed that the population of India had reached 1.324 billion. This population count was a significant increase from the previous census conducted in 2001, which recorded a population of 1.028 billion. The population growth rate during this period was approximately 17.64%.

Key factors contributing to the population increase:

1. High Birth Rate: India has traditionally had a high birth rate, which has contributed to the population growth. The birth rate refers to the number of births per 1,000 people in a given year.

2. Declining Death Rate: The death rate in India has been decreasing due to improvements in healthcare, sanitation, and overall living conditions. This has led to an increase in life expectancy and a higher population.

3. Improved Infrastructure: The development of infrastructure, such as better transportation and healthcare facilities, has contributed to improved access to services and a decline in mortality rates.

4. Social Factors: Cultural and social factors, such as the preference for large families and the limited availability of family planning resources in some regions, have also played a role in the population growth.

Impact of population growth:

1. Pressure on Resources: The growing population puts pressure on resources such as land, water, and energy. This can lead to issues such as scarcity, environmental degradation, and increased competition for resources.

2. Urbanization: The increase in population has resulted in rapid urbanization, with a significant migration of people from rural areas to urban centers. This has led to challenges in infrastructure development and the provision of basic services in cities.

3. Employment: The growing population poses a challenge in terms of providing employment opportunities for a large number of people, particularly in sectors such as agriculture and manufacturing.

In conclusion, the population of India according to the 2011 Census was 1.324 billion. Factors such as high birth rates, declining death rates, improved infrastructure, and social factors have contributed to this population growth. The increasing population has both positive and negative implications, requiring careful planning and management to ensure sustainable development and well-being for all citizens.