Australia Day is the official national day of Australia. Observed annually on 26 January, it marks the 1788 landing of the First Fleet and raising of the Union Flag of Great Britain by Arthur Phillip at Sydney Cove, a small bay on the southern shore of Sydney Harbour. In present-day Australia, the government Australia Day Council organises events that seeks to recognise the contributions of Australians to the nation, while also encouraging reflection on past wrongs including towards Indigenous Australians and also giving respect and celebrating the diversity and achievements of Australian society past and present. The presentation of community awards and citizenship ceremonies are also commonly held on the day. The holiday is marked by the presentation of the Australian of the Year Awards on Australia Day Eve, announcement of the Australia Day Honours list and addresses from the governor-general and prime minister. It is an official public holiday in every state and territory. With community festivals, concerts and citizenship ceremonies, the day is celebrated in large and small communities and cities around the nation. Australia Day has become the biggest annual civic event in Australia.

Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. Australia is the largest country by area in Oceania and the world's sixth-largest country. Australia is the oldest, flattest, and driest inhabited continent, with the least fertile soils. It is a megadiverse country, and its size gives it a wide variety of landscapes and climates, with deserts in the centre, tropical rainforests in the north-east, tropical savannas in the north, and mountain ranges in the south-east.