When australia became one country?

On 1 January 1901, the six separate British colonies of New South Wales, Queensland, South Australia, Tasmania, Victoria, and Western Australia came together to form a federated nation called the Commonwealth of Australia. This date marks the birth of Australia as a nation. Since then, Australia has grown and evolved over the years, but 1 January 1901 remains a significant day in its history as the day it officially became one united country.