Several entities go by the name "cities" in colloquial terms:
Municipalities – These have many different types across Canada, ranging from cities to rural districts. See List of the 100 largest municipalities in Canada by population.
Metropolitan areas – Statistics Canada defines these as census metropolitan areas. See List of the 100 largest metropolitan areas in Canada.
Population centres (formerly urban areas) – Statistics Canada delineates population centres (formerly urban areas) based on continuous population density, regardless of municipal boundaries. See List of the 100 largest population centres in Canada.
