Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. It is the largest country in Oceania and the world’s sixth-largest country. Australia’s population of nearly 26 million, in an area of 7,617,930 square kilometers (2,941,300 sq. mi), is highly urbanized and heavily concentrated on the eastern seaboard. Canberra is the nation’s capital, while the largest city is Sydney, and other major metropolitan areas are Melbourne, Brisbane, Perth, and Adelaide.