Census is the process of collecting, compiling, and publishing demographic, economic, and social data pertaining to specified time or times to all people in the country or territory.
Census can be classified according to time interval it takes from one census to another or approach of undertaking the census.
Classification of census according to the time interval
According to time internal census can be classified as either quinquennial (census carried out after every five years) or decennial census (census carried out after every ten years).
Classification of census according to approach
According to the approach, census can be either de jure census or de facto census.
De jure census
this is one in which the people are counted according to their usual place of residence, where only permanent members of the household are counted.
De facto census
this is an approach to undertaking a census in which people are counted wherever they are found on the day of census exercise, that is all people who stayed in the homeland for the night are counted.