The Commonwealth of Australia was formed on the 1st January 1901 with the proclamation of the Commonwealth of Australia Constitution Act, an act of the Imperial Parliament at Westminster (London, England). This formed a federation of the six former Australian colonies which thereafter became states of the Commonwealth. In addition, the continental island included a territory which became known as the Northern Territory. In 1926 the national capital was established at Canberra and an area around the capital became known as the Australian Capital Territory. These two territories have become the two self-governing internal territories.
Over time, the Commonwealth acquired other external (ie not on the Australian mainland) territories. A number of these have never been the home of permanent populations although some are staffed year round as weather and/or research stations.
For a period, Australia governed first Papua and later New Guinea (a trust territory). From 1949 these territories were administered from Canberra as the Territory of Papua New Guinea until their independence in 1975 when they became Papua New Guinea.
Click on name of the area on either the map or the list of states and territories below for further information.