The first human habitation of Australia is estimated to have occurred between 42,000 and 48,000 years ago. These first Australians were the ancestors of the current Indigenous Australians; they arrived via land bridges and short sea-crossings from present-day South-East Asia. The Torres Strait Islanders, ethnically Melanesian, inhabited the Torres Strait Islands and parts of far-north Queensland; their cultural practices were and remain distinct from those of the Aborigines.

The Commonwealth of Australia is a constitutional monarchy, a federation, and a parliamentary democracy. The Commonwealth of Australia was formed in 1901 as a result of an agreement between what were previously six self-governing British colonies. The terms of this agreement are embodied in the Australian Constitution, which was drawn up at a Constitutional Convention and ratified by the people of the colonies at referendums. The structure of the Australian Government may be examined in light of two distinct concepts, namely federalism and the separation of powers into legislative, executive and judiciary branches of government.

The Economy of Australia is a prosperous, Western-style market economy, with a per capita GDP slightly higher than United Kingdom, France and Germany. The Australian economy is dominated by its services sector (68% of GDP), yet it is the agricultural and mining sectors (8% of GDP combined) that account for 65% of its exports. Rich in natural resources, Australia is a major exporter of agricultural products, particularly grains and wool, and minerals, including various metals, coal, and natural gas. A downturn in world commodity prices can thus have a large impact on the economy.

The demography of Australia cover basic statistics, most populous cites, ethnicity and religious affiliation. The population of Australia is growing at a rate of 1.2% per year and officially reached 20 million people on 4 December 2003. Australia is the 53rd most populous country in the world and its population is largely urban with a majority identifying themselves as Christian. English is the national language, and is spoken and written in a distinct variety known as Australian English. According to the 2001 census, English is the only language spoken in the home for around 80% of the population. The next most common languages spoken at home are Chinese language (2.1%), Italian (1.9%) and Greek (1.4%). A considerable proportion of first- and second-generation migrants are bilingual.

The modern culture of Australia is a Western culture and draws from many sources, primarily from the Anglo-Celtic cultures, but also from indigenous Australians, the multi-ethnic immigration associated with the Australian gold rushes of the 1850s, and post-World War II immigrants from all over the world. Mainstream Australian culture has been strongly influenced by British culture and European culture, and more recently the culture of the United States of America. There are, however, distinctive influences from the Australian natural environment, the country's settler history, indigenous Australians, geographical isolation from other Western nations and proximity to Asia.

Although most of Australia is semi-arid or desert, it covers a diverse range of habitats, from alpine heaths to tropical rainforests, and is recognised as a megadiverse country. Because of the great age and consequent low levels of fertility of the continent, its extremely variable weather patterns, and its long-term geographic isolation, much of Australia's biota is unique and diverse. Well-known Australian fauna include monotremes (the platypus and echidna); a host of marsupials, including the kangaroo, koala, wombat; and birds such as the emu and kookaburra. The dingo was introduced by Austronesian people who traded with Indigenous Australians around 3000 BCE.