Perth is a capital city in a country.
Australia ( [ əˈstreɪliə ] , [ ɒ - ] , [ - ljə ] ) , officially the Commonwealth of Australia , is a country comprising the mainland of the Australian continent , the island of Tasmania and numerous smaller islands . A capital city ( or simply capital ) is the municipality exercising primary status in a country , state , province , or other region , usually as its seat of government . Perth is the capital and largest city of the Australian state of Western Australia .