"Advance Australia Fair" was composed by Scottish-born Peter Dodds McCormick in 1878, making the song itself over 145 years old. It was first performed at a banquet in Sydney celebrating the opening of the Sydney International Exhibition.
The original four verses were reduced to two for official use, and lyrics were modified to be more inclusive (e.g., "Australia's sons" became "Australians all"). The anthem's melody and words reflect 19th-century colonial patriotism, yet its endurance speaks to its adaptability as a national symbol.
So while the song dates to 1878, it has been the official national anthem only since 1984—a 106-year gap between creation and formal adoption.