Each district is further divided in to sub-districts, which are known differently in different parts in the country (e.g., tahsil, taluka, community development (CD) block, Police station, Mandal, revenue circle, etc.).
The lowest primary administrative units of administration are the villages in rural areas and towns in urban areas.
At the time of Census 2001, there were about 6.39 lakh villages in the country, out of which about 44,856 have been uninhabited villages.
The villages are of different sizes in terms of population depending upon the geography of the area, availability of land and water, etc. The population living in the villages comprises the rural population of the country.
The number of towns in the country at the time of Census 2001 was 5,161. The towns include statutory towns (as notified by government) and census towns as identified by the census organization on the basis of well defined criteria.
When towns grow in are and population, the areas adjoining the notified core town(s) also may acquire urban characteristics.
Therefore, for proper representation, the Census also provides data on the Urban Agglomerations (UAs), which comprise core town(s) and its outgrowths meeting the urban characteristics.
Delhi, Kolkata, Chennai, Mumbai are examples of such Urban Agglomerations.
There are 384 Urban Agglomerations in the country. The number of UAs and towns at the Census 2001 was 4,378. The population living in the urban areas comprises the urban population of the country.
All the villages and towns usually form part of a sub – district. There are however towns which extend beyond the limits of a district (e.g., Delhi, Srinagar, etc.).
There are a few districts that are fully urban (Mumbai, Kolkata, Chennai, Hyderabad, etc.) and a few districts that are fully rural.
Census data are made available for the country as a whole and by state, union territory, district, sun-district, UA and town.
For a few important characteristics, these are also made available down to village level in rural areas and ward level in towns.