The history of Australia is the history of the land and peoples of the continental land mass and offshore territories which now comprise the Commonwealth of Australia. The Commonwealth of Australia came into existence on 1 January 1901 as a federation of former British colonies, however the human history of Australia commences with the arrival of the first ancestors of Aboriginal Australians by sea from Maritime Southeast Asia between 50,000 and 65,000 years ago, and continues to the present day multicultural democracy.

Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. Australia is the largest country by area in Oceania and the world's sixth-largest country. Australia is the oldest, flattest, and driest inhabited continent, with the least fertile soils. It is a megadiverse country, and its size gives it a wide variety of landscapes and climates, with deserts in the centre, tropical rainforests in the north-east, tropical savannas in the north, and mountain ranges in the south-east.