 Australia ( / əˈstreɪliə / , / ɒ- / , / -jə / ) , officially the Commonwealth of Australia , is a country comprising the mainland of the Australian continent , the island of Tasmania , and numerous smaller islands . It is the world 's sixth @-@ largest country by total area . Neighbouring countries include 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 . 
