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 by total area. The neighbouring countries are Papua New Guinea, Indonesia and East Timor to the north; the Solomon Islands and Vanuatu to the north-east; and New Zealand to the south-east.
The population of 25 million is highly urbanised.Australia's capital is Canberra, and the largest city is Sydney. The country's other major metropolitan areas are Melbourne, Brisbane, Perth and Adelaide.
The country is known for the Sydney Opera House, the Great Barrier Reef, its wilderness and desert known as the Outback and unique animal species such as kangaroo and platypus.
The flag of Australia is a defaced Blue Ensign: a blue field with the Union Jack in the canton (upper hoist quarter), and a large white seven-pointed star known as the Commonwealth Star in the lower hoist quarter