The Census of Population is the most widely-used and trusted source of Canadian demographic data. Every five years, Statistics Canada counts the number of people in each Canadian household and collects information about them. This provides a rich portrait of Canadians over time.
By law, every Canadian household must complete the basic Census form which asks 10 questions in order to count people, gather some demographic information (age, sex, language), establish the relationships between people in households, and find out what types of homes people live in.
A smaller sample of households* must also fill out a supplementary 'long-form Census' with about 60 questions about income, occupation, and many other things. The data from the short and long forms are combined to give a very detailed and reliable profile of Canadians.
* Until 2006, one in five Canadian households (20%) filled out the long form; since 2016, one in four (25%) have done so.
Note: in 2011 only, the mandatory long-form Census was replaced with a voluntary National Household Survey (NHS).