The word colonialism is often a misnomer, used for any form of domination of one society over another. The original Greek meaning of a colony implied an outward migration from a mother city or metropolis to settle in a new place. True colonization in this original sense is represented today by examples such as the United States and Canada, where culture change took place but was mainly carried by a blanket immigration of Europeans who brought their culture with them. The Native Americans were pushed aside to become a small minority, sometimes culturally assimilated, sometimes not.

Another variety of so-called colonialism is demographically the reverse of true colonization. It is more accurately labeled territorial empire, where Europeans conquered a territory overseas but sent a negligible number of settlers beyond the administrative and military personnel required to control it. Examples of this type would be British rule in India and Nigeria.

A third, mixed case, midway between territorial empire and true colonization, also sometimes occurred. In these instances, European settlers were a substantial minority, living alongside other cultural communities of native inhabitants. The result is often called a plural society. A rough line between plural societies and true empires can be drawn when the settler community reaches more than about 5 percent of the total population. The important instances of plural societies in the past century or so are South Africa, Algeria, Israel, some Latin American countries, such as Peru or Guatemala, and many parts of the former Soviet Union.