The first census in India took place in 1872 during the British rule. Here are some details regarding the first census:

Background:
- The British government in India decided to conduct a census to gather information about the population and resources of the country.
- The idea was to use the data to facilitate better governance and administration.

Process:
- The census was conducted under the guidance of Lord Mayo, who was the Viceroy of India at that time.
- The census was conducted by British officials who were aided by local officials and interpreters.
- The data was collected through a house-to-house enumeration method, where the enumerators visited every household and recorded the necessary information.

Data collected:
- The census collected data on various parameters such as age, sex, occupation, religion, caste, and language.
- The total population of India was recorded as 238 million, which was further classified into various categories based on the above parameters.
- The data also provided insights into the literacy rate, urbanization, and other demographic trends.

Significance:
- The first census in India was significant as it provided a baseline for future censuses and helped in the formulation of policies and programs.
- The data helped the British government in India to understand the social and economic conditions of the country and to plan accordingly.
- The census also helped in the development of statistical methods and techniques that were later used in other countries.

In conclusion, the first census in India was conducted in 1872 under the British rule, and it provided valuable insights into the population and resources of the country. The data collected during the census helped in the formulation of policies and programs and contributed to the development of statistical methods and techniques.

First census was started in 1872 but that was not completely done...but in next decade that is in 1881 was fully completed...but according to given question 1872 is right answer