The Australian Defence Force Ensign is a flag of Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 which represents the tri-service Australian Defence Force

Australian Defence Force

The Australian Defence Force is the military organisation responsible for the defence of Australia. It consists of the Royal Australian Navy , Australian Army, Royal Australian Air Force and a number of 'tri-service' units...

. The flag was declared a "Flag of Australia" under Section 5 of the Flags Act 1953

Flags Act 1953

The Flags Act 1953 is an act of the Parliament of Australia which defines the official Flag of Australia. Queen Elizabeth II gave Royal Assent on 14 February 1954 after opening the Commonwealth Parliament during her 1954 Royal Tour...

on 14 April 2000.

The Royal Australian Navy

Royal Australian Navy

The Royal Australian Navy is the naval branch of the Australian Defence Force. Following the Federation of Australia in 1901, the ships and resources of the separate colonial navies were integrated into a national force: the Commonwealth Naval Forces...

 and Air Force

Royal Australian Air Force

The Royal Australian Air Force is the air force branch of the Australian Defence Force. The RAAF was formed in March 1921. It continues the traditions of the Australian Flying Corps , which was formed on 22 October 1912. The RAAF has taken part in many of the 20th century's major conflicts...

 have ensigns, the Royal Australian Navy Ensign

Royal Australian Navy Ensign

The Australian White Ensign is a naval ensign used by ships of the Royal Australian Navy from 1967 onwards. From the formation of the RAN until 1967, Australian warships used the British White Ensign as their ensign...

 and the Royal Australian Air Force Ensign

Royal Australian Air Force Ensign

The Royal Australian Air Force Ensign is used by the Royal Australian Air Force in Australia and overseas. It is based on the Australian national flag, with the field changed to Air Force blue, and the southern cross tilted clockwise to make room for the RAAF roundel inserted in the lower fly...

. The Army

Australian Army

The Australian Army is Australia's military land force. It is part of the Australian Defence Force along with the Royal Australian Navy and the Royal Australian Air Force. While the Chief of Defence commands the Australian Defence Force , the Army is commanded by the Chief of Army...

 has historically used the Australian Flag

Flag of Australia

The flag of Australia is a defaced Blue Ensign: a blue field with the Union Flag in the canton , and a large white seven-pointed star known as the Commonwealth Star in the lower hoist quarter...

. The Defence Ensign is supposed to be used in the case of joint activities. It is made up of three vertical bands: dark blue, red and light blue, representing the navy, army and air force respectively. In the centre is a large joint services emblem in yellow. This emblem features an anchor, crossed swords and a wedge-tailed eagle with wings outstretched combined above a boomerang and below a crest featuring a seven pointed Commonwealth Star.

The rank flags of staff with joint services commands, such as the Chief of Defence Force and the Minister for Defence, are derived from the Defence Force Ensign.