Australia, officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent (the world's smallest), the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans.N4 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 around 250 language groups of indigenous Australians. 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 were established during the 19th century.
On 1 January 1901, the six colonies became a federation and the Commonwealth of Australia was formed. Since Federation, Australia has maintained a stable liberal democratic 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 and Adelaide. The nation's capital city is Canberra, in the Australian Capital Territory.