'''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 by area in Oceania and the world's sixth-largest country. Australia's population of nearly  million, in an area of , is highly urbanised and heavily concentrated on the eastern seaboard. Canberra is the nation's capital, while the largest city is Sydney, and other major metropolitan areas include Melbourne, Brisbane, Perth, and Adelaide.