The flag of Australia is a defaced Blue Ensign: a blue field with the Union Flag in the canton (upper hoist quarter), and a large white seven-pointed star known as the Commonwealth Star in the lower hoist quarter.
The Australian flag fly contains a representation of the Southern Cross constellation, made up of five white stars – one small five-pointed star and four, larger, seven-pointed stars. In addition, there are other official flags representing Australia, its people and core functions of government.
The Australian flag’s original design (with a six-pointed Commonwealth Star) was chosen in 1901 from entries in a worldwide competition held following Federation, and was first flown in Melbourne on 3 September 1901. A slightly different design was approved by King Edward VII in 1902. Over the next few years, the exact specifications of the flag were changed several times both intentionally and as a result of confusion. The current specifications were formally gazetted in 1934, and in 1954 the flag became recognised by, and legally defined in, the Flags Act 1953, as the “Australian National Flag“. – Wikipedia