Being the flattest and driest inhabited continent, with the oldest and least fertile soils, Australia has a landmass of 7,617,930 square kilometres (2,941,300 sq mi). A megadiverse country, its size gives it a wide variety of landscapes, with deserts in the centre, tropical rainforests in the north-east and mountain ranges in the south-east. A gold rush began in Australia in the early 1850s, which boosted the population of the country. Nevertheless, its population density, 2.8 inhabitants per square kilometre, remains among the lowest in the world. Australia generates its income from various sources including mining-related exports, telecommunications, banking and manufacturing.Indigenous Australian rock art is the oldest and richest in the world, dating as far back as 60,000 years and spread across hundreds of thousands of sites.
The name Australia (pronounced [əˈstɹæɪljə, -liə] in Australian English) is derived from the LatinTerra Australis ("southern land"), a name used for a hypothetical continent in the Southern Hemisphere since ancient times. When Europeans first began visiting and mapping Australia in the 17th century, the name Terra Australis was naturally applied to the new territories.[N 4]
Until the early 19th century, Australia was best known as "New Holland", a name first applied by the Dutch explorer Abel Tasman in 1644 (as Nieuw-Holland) and subsequently anglicised. Terra Australis still saw occasional usage, such as in scientific texts.[N 5] The name Australia was popularised by the explorer Matthew Flinders, who said it was "more agreeable to the ear, and an assimilation to the names of the other great portions of the earth". The first time that Australia appears to have been officially used was in April 1817, when Governor Lachlan Macquarie acknowledged the receipt of Flinders' charts of Australia from Lord Bathurst. In December 1817, Macquarie recommended to the Colonial Office that it be formally adopted. In 1824, the Admiralty agreed that the continent should be known officially by that name. The first official published use of the new name came with the publication in 1830 of The Australia Directory by the Hydrographic Office.
Colloquial names for Australia include "Oz" and "the Land Down Under" (usually shortened to just "Down Under"). Other epithets include "the Great Southern Land", "the Lucky Country", "the Sunburnt Country", and "the Wide Brown Land". The latter two both derive from Dorothea Mackellar's 1908 poem "My Country".