Australia, or the Commonwealth of Australia, is a sovereign state made up of the Australian continent's interior, the island of Tasmania, as well as a number of other smaller islands. Australia is the sixth-biggest nation in the world and the largest country in Oceania by area. Australia is the oldest, flattest, driest,[ and least fertile inhabited continent. With deserts in the center, tropical rainforests in the northeast, tropical savannas in the north, and mountain ranges in the southeast, it is a megadiverse country with a broad diversity of landscapes and temperatures.
Australia has one of the highest per capita incomes in the world and a highly developed market economy. Australia is a regional power and spends more on its military than any other country in the world. The United Nations, the G20, the OECD, the World Trade Organization, the Asia-Pacific Economic Cooperation, the Pacific Islands Forum, the Pacific Community, the Commonwealth of Nations, and the defense/security organizations ANZUS, AUKUS, and the Five Eyes are among the international organizations it is a member of. It is a significant American ally outside of NATO.