The mainland of the continent of Australia has been inhabited for more than 42,000 years by Indigenous Australians. After sporadic visits by fishermen from the north and by European explorers and merchants starting in the seventeenth century, the eastern half of the mainland was claimed by the British in 1770 and officially settled through penal transportation as the colony of New South Wales on 26 January 1788. As the population grew and new areas were explored, another five largely self-governing Crown Colonies were successively established over the course of the nineteenth century.

On 1 January 1901, the six colonies federated and the Commonwealth of Australia was formed. Since federation, Australia has maintained a stable liberal democratic political system and remains a Commonwealth Realm. The capital city is Canberra, located in the self-governing Australian Capital Territory. The current national population is around 20.6 million people, and is concentrated mainly in the large coastal cities of Sydney, Melbourne, Brisbane, Perth, and Adelaide.

The name Australia is derived from the Latin Australis, meaning of the South. Legends of an "unknown land of the south" (terra australis incognita) dating back to Roman times were commonplace in mediaeval geography, but they were not based on any actual knowledge of the continent. The Dutch adjectival form Australische was used by Dutch officials in Batavia to refer to the newly discovered land to the south as early as 1638. The first use of the word "Australia" in English was a 1693 translation of Les Aventures de Jacques Sadeur dans la Découverte et le Voyage de la Terre Australe, a 1692 French novel by Gabriel de Foigny under the pen name Jacques Sadeur.[1] Alexander Dalrymple then used it in An Historical Collection of Voyages and Discoveries in the South Pacific Ocean (1771), to refer to the entire South Pacific region. In 1793, George Shaw and Sir James Smith published Zoology and Botany of New Holland, in which they wrote of "the vast island, or rather continent, of Australia, Australasia or New Holland."

The name "Australia" was popularised by the 1814 work A Voyage to Terra Australis by the navigator Matthew Flinders who was the first person to circumnavigate Australia. Despite its title, which reflected the view of the Admiralty, Flinders used the word "Australia" in the book, which was widely read and gave the term general currency. Governor Lachlan Macquarie of New South Wales subsequently used the word in his dispatches to England. In 1817, he recommended that it be officially adopted. In 1824, the British Admiralty agreed that the continent should be known officially as Australia.

The first human habitation of Australia is estimated to have occurred between 42,000 and 48,000 years ago.[2] The first Australians were the ancestors of the current Indigenous Australians; they arrived via land bridges and short sea-crossings from present-day Southeast Asia. Most of these people were hunter-gatherers, with a complex oral culture and spiritual values based on reverence for the land and a belief in the Dreamtime. The Torres Strait Islanders, ethnically Melanesian, inhabited the Torres Strait Islands and parts of far-north Queensland; they possess cultural practices distinct from the Aborigines.

The first undisputed recorded European sighting of the mainland of the Australian continent was made by the Dutch navigator Willem Janszoon, who sighted the coast of Cape York Peninsula in 1606. During the seventeenth century, the Dutch charted the whole of the western and northern coastlines of what they called New Holland, but made no attempt at settlement. In 1770, James Cook sailed along and mapped the east coast of Australia, which he named New South Wales and claimed for Britain. The expedition's discoveries provided impetus for the establishment of a penal colony there following the loss of the American colonies that had previously filled that role.

The British Crown Colony of New South Wales started with the establishment of a settlement at Port Jackson by Captain Arthur Phillip on 26 January 1788. This date was later to become Australia's national day, Australia Day. Van Diemen's Land, now known as Tasmania, was settled in 1803 and became a separate colony in 1825. The United Kingdom formally claimed the western part of Australia in 1829. Separate colonies were created from parts of New South Wales: South Australia in 1836, Victoria in 1851, and Queensland in 1859. The Northern Territory (NT) was founded in 1863 as part of the Province of South Australia. South Australia was founded as a "free province" — that is, it was never a penal colony. Victoria and Western Australia were also founded "free", but later accepted transported convicts. The transportation of convicts to Australia was phased out between 1840 and 1864.

Australia's 7,686,850 square kilometres (2,967,909 sq. mi) landmass is on the Indo-Australian Plate. Surrounded by the Indian, Southern and Pacific oceans, Australia is separated from Asia by the Arafura and Timor seas. Australia has a total 25,760 kilometres (16,007 mi) of coastline and claims an extensive Exclusive Economic Zone of 8,148,250 square kilometres (3,146,057 sq. mi). This exclusive economic zone does not include the Australian Antarctic Territory.

The Great Barrier Reef, the world's largest coral reef, lies a short distance off the north-east coast and extends for over 2,000 kilometres (1,250 mi). The world's largest monolith, Mount Augustus, is located in Western Australia. At 2,228 metres (7,310 ft), Mount Kosciuszko on the Great Dividing Range is the highest mountain on the Australian mainland, although Mawson Peak on the remote Australian territory of Heard Island is taller at 2,745 metres (9,006 ft).

By far the largest part of Australia is desert or semi-arid. Australia is the driest inhabited continent, the flattest, and has the oldest and least fertile soils. Only the south-east and south-west corners of the continent have a temperate climate. The northern part of the country, with a tropical climate, has a vegetation consisting of rainforest, woodland, grassland, mangrove swamps and desert. Climate is highly influenced by ocean currents, including the El Niño southern oscillation, which is correlated with periodic drought, and the seasonal tropical low pressure system that produces cyclones in northern Australia.