The House listing phase began on 1 April 2010 and involved the collection of information about all buildings.

According to the provisional reports released on 31 March 2011, the Indian population increased to 1.21 billion with a decadal growth of 17.70%.

Spread across 28 states[a] and 8 union territories, the census covered 640 districts, 5,924 sub-districts, 7,935 towns and more than 600,000 villages.

A total of 2.7 million officials visited households in 7,935 towns and 600,000 villages, classifying the population according to gender, religion, education and occupation.

[3] Information on castes was included in the census following demands from several ruling coalition leaders including Lalu Prasad Yadav, and Mulayam Singh Yadav supported by opposition parties Bharatiya Janata Party, Shiromani Akali Dal, Shiv Sena and All India Anna Dravida Munnetra Kazhagam.

[6] Earlier, there was speculation that there would be a caste-based census conducted in 2011, the first time in 80 years (last was in 1931), to find the exact population of the "Other Backward Classes" (OBCs) in India.

[7][8][9][10] This was later accepted and the Socio Economic and Caste Census 2011 was conducted whose first findings were revealed on 3 July 2015 by Union Finance Minister Arun Jaitley.

The first, the house-listing phase, began on 1 April 2010 and involved collection of data about all the buildings and census houses.

The eradication of epidemics, the availability of more effective medicines for the treatment of various types of diseases and the improvement in the standard of living were the main reasons for the high decadal growth of population in India.

[59][60][61] There are six religions in India that have been awarded "National Minority" status – Muslims, Christians, Sikhs, Jains, Buddhists and Parsis.

[62][63] Sunnis, Shias, Bohras, Agakhanis and Ahmadiyyas were identified as sects of Islam in India.

[64][65][66] As per 2011 census, six major faiths- Hindus, Muslims, Christians, Sikhs, Buddhists, Jains make up over 99.4% of India's 1.21 billion population, while "other religions, persuasions" (ORP) count is 8.2 million.

[69] The 2011 census report on bilingualism and trilingualism, which provides data on the two languages in order of preference in which a person is proficient other than the mother tongue, was released in September 2018.

Any individual above age seven who can read and write in any language with an ability to understand was considered literate.