Australia (IPAc-enicon??stre?lj? respell?STRAYLy? or IPAc-en??stre?lj? respelloSTRAYLy?, or IPAc-en???stre?li? respellawSTRAYlee-?), officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent (Australia (continent)) (the worlds smallest), the island of Tasmania, and numerous smaller islands (list of islands of Australia) in the Indian (Indian Ocean) and Pacific Oceans.RefSouthern OceanN4 Neighbouring countries include Indonesia, East Timor, and Papua New Guinea to the north, the Solomon Islands, Vanuatu, and New Caledonia to the northeast, and New Zealand to the southeast.

For at least 40,000 years before European settlement in the late 18th century, the Australian mainland and Tasmania were inhabited by indigenous Australians, who spoke around 250 language groups (Indigenous Australian languages) After sporadic visits by fishermen from the immediate north, and discovery by Dutch explorers in 1606, the eastern half of Australia was claimed by the British in 1770 and initially settled through penal transportation to the colony of New South Wales, founded on 26 January 1788. The population grew steadily in the following years; the continent was explored, and another five largely self-governing Crown Colonies (British overseas territories) were established during the 19th century.

On 1 January 1901, the six colonies became a federation (Federation of Australia) and the Commonwealth of Australia was formed. Since Federation, Australia has maintained a stable liberal democratic (liberal democracy) political system and remains a Commonwealth realm. The population is 22 million, with approximately 60% concentrated in and around the mainland state capitals of Sydney, Melbourne, Brisbane, Perth (Perth, Western Australia) and Adelaide. The nations capital city is Canberra, in the Australian Capital Territory.

Australia is a prosperous developed country with a multicultural society. It ranks highly in many international comparisons of national performance such as human development, quality of life, health care, life expectancy, public education, economic freedom and the protection of civil liberties and political rights. Australian cities rank among the worlds highest in terms of cultural offerings and quality of life. It is a member of the United Nations, G20, Commonwealth of Nations, OECD (Organisation for Economic Cooperation and Development), APEC (Asia-Pacific Economic Cooperation), Pacific Islands Forum and the World Trade Organization.