The Dominions was an old British name, no longer used in ordinary talk, for countries such as Australia, Canada, and New Zealand in the early twentieth century. Those places already had their own governments, but they still belonged to the British Empire: the same king, and Britain still spoke for them in some world affairs. You will meet the word in history books, old newspapers, and war memorials — 'soldiers from the Dominions' — not in today's politics. Canada and Australia do not call themselves Dominions now. Britain also used the same old label for a few other places, such as South Africa, but the learner's sense you are studying points first at Australia, Canada, and New Zealand. It is a capital-D history name, not the everyday word dominion for 'power over a place'.