Australia, also known as the Commonwealth of Australia, is the sixth-largest country based on total area. It is a sovereign country that makes up the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. It is neighbored by several countries, including Papua New Guinea, Indonesia, East Timo, the Solomon Islands, Vanuatu and New Zealand. The country has a population of 26 million. Australia is highly urbanised and most of the population resides on the eastern seaboard. The capital is Canberra, and its largest city is Sydney, though it houses several major metropolitan areas, including Melbourne, Brisbane, Perth, and Adelaide.