Any land within Australia’s national border that is not part of one of the states is called a territory.
The Northern Territory, the Australian Capital Territory and Jervis Bay are mainland territories.
Ashmore and Cartier Islands, Christmas Island, the Cocos (Keeling) Islands, the Coral Sea Islands, and Norfolk Island are external territories.
The Australian Antarctic Territory and the sub-Antarctic Territory of Heard Island and McDonald Islands are also external territories (however, they are governed differently to the other external territories).
What is a Commonwealth place?
Commonwealth place means a place acquired by the Commonwealth for public purposes, other than the seat of government (Canberra).