Australia , officially the Commonwealth of Australia, is a country in the southern hemisphere comprising the mainland, which is both the world's smallest continent and the world's largest island, the island of Tasmania, and numerous other islands in the Indian and Pacific Oceans. Australia is the only place that is simultaneously considered a continent, a country and an island. Neighbouring countries include Indonesia, East Timor and Papua New Guinea to the north, the Solomon Islands, Vanuatu and New Caledonia to the north-east and New Zealand to the southeast.

For around 40,000 years before European settlement commenced in the late 18th century, the Australian mainland and Tasmania were inhabited by around 250 individual nations of indigenous Australians. After sporadic visits by fishermen from the immediate north, and European 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 during the 19th century another five largely self-governing Crown Colonies were established.

Technologically advanced and industrialised, Australia is a prosperous multicultural country and has excellent results in many international comparisons of national performance such as health care, life expectancy, human development, public education, economic freedom, and the protection of civil liberties and political rights. Australian cities also routinely rank among the world's highest in terms of livability, cultural offerings, and quality of life.