Indigenous Australians are people with familial heritage from, and/or recognised membership of, the various ethnic groups living within the territory of present day Australia prior to British colonisation. They consist of two distinct groups, which includes many ethnic groups: the Aboriginal Australians of the mainland and many islands, including Tasmania, and the Torres Strait Islanders of the seas between Queensland and Papua New Guinea, located in Melanesia. The term Aboriginal and Torres Strait Islander peoples or the person's specific cultural group, is often preferred, though the terms First Nations of Australia, First Peoples of Australia and First Australians are also increasingly common; 812,728 people self-identified as being of Aboriginal and/or Torres Strait Islander origin in the 2021 Australian Census, representing 3.2% of the total population of Australia. Of these Indigenous Australians, 91.4% identified as Aboriginal; 4.2% identified as Torres Strait Islander; while 4.4% identified with both groups. Since 1995, the Australian Aboriginal flag and the Torres Strait Islander flag have been official flags of Australia.

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.