Australia is not part of the United Kingdom. Historically, Australia was settled as a series of six colonies by the British Empire in the late 18th century. These colonies formed a federation on Jan. 1, 1901, and the Commonwealth nation of Australia was born.
The country became a dominion, or autonomous sovereign nation still maintaining allegiance to the British monarchy, in 1907. This status changed in 1942 when Australia voted to sever constitutional ties with the United Kingdom and again in 1986 with the passage of the Australia Act. The Australia Act recognized Australia as a member of the Commonwealth nations, sharing the British monarchy, but entirely self-governed separately of the United Kingdom.