Australia, formally the Commonwealth of Australia, is a sovereign entity that includes the Australian continent's mainland, the island of Tasmania, and a number of smaller islands. Australia is the biggest nation by size in Oceania and the world's sixth-largest country, with an area of 7,617,930 square kilometers (2,941,300 square miles). Australia is the world's oldest, flattest, and driest continent, with the least productive soils. It is a megadiverse nation with a diverse range of terrain and climates, including deserts in the center, tropical rainforests in the northeast, and mountain ranges in the southeast.
Indigenous Australians have lived on the continent for around 65,000 years. With the advent of Dutch explorers in the early 17th century, European naval exploration of Australia began. The eastern half of Australia was claimed by Great Britain in 1770 and was originally inhabited by convict transportation to the colony of New South Wales beginning on January 26, 1788, which became Australia's national day. In the next decades, the European population slowly increased, and by the time of the 1850s gold rush, much of the continent had been explored by European immigrants, with an additional five self-governing crown colonies formed. The six colonies united on January 1, 1901, becoming the Commonwealth of Australia. Since then, Australia has maintained a stable liberal democratic political system and a prosperous market economy.
Australia is a federal parliamentary constitutional monarchy made up of six states and 10 territories. The population of almost 26 million people in Australia is highly urbanized and largely concentrated on the eastern shore. The nation's capital is Canberra, and the five major cities are Sydney, Melbourne, Brisbane, Perth, and Adelaide. Australia's demographics have been affected by centuries of immigration, with immigrants accounting for 30% of the population, the largest percentage among major Western countries. Australia's enormous natural resources and well-developed international trade links are critical to the country's economy, which earns money from a variety of areas such as services, mining exports, finance, manufacturing, agriculture, and international education.
Australia is a developed nation with a high-income economy; it has the thirteenth-largest economy in the world, the tenth-highest per capita income, and the eighth-highest Human Development Index. Australia is a regional power with the thirteenth greatest military spending in the world. Australia rates well in terms of quality of life, democracy, health, education, economic freedom, civil liberties, safety, and political rights, with all of its main cities excelling in worldwide comparative livability surveys. It is a member of the United Nations, the G20, the OECD, the World Trade Organization, ANZUS, AUKUS, the Five Eyes, the Quad, APEC, the Pacific Islands Forum, the Pacific Community, and the Commonwealth of Nations.