Australia, officially the Commonwealth of Australia, is the only country that has a whole continent to itself. Although it is world famous for its natural wonders and wide open spaces, its beaches, deserts, "the bush", and "theOutback", Australia is actually one of the world's most highly urbanised countries with vibrant, cosmopolitan cities such as Melbourne, Brisbane, Sydney and Perth.
Although most of Australia is semi-arid or desert, it includes a diverse range of habitats from alpine heaths to tropical rainforests, and is recognised as a megadiverse country. Fungi typify that diversity; an estimated 250,000 species—of which only 5% have been described—occur in Australia.Because of the continent's great age, extremely variable weather patterns, and long-term geographic isolation, much of Australia's biota is unique. About 85% of flowering plants, 84% of mammals, more than 45% of birds, and 89% of in-shore, temperate-zone fish are endemic.Australia has the greatest number of reptiles of any country, with 755 species.
Australian forests are mostly made up of evergreen species, particularly eucalyptus trees in the less arid regions; wattles replace them as the dominant species in drier regions and deserts.Among well-known Australian animals are the monotremes (the platypus and echidna); a host of marsupials, including the kangaroo, koala, and wombat, and birds such as the emu and the kookaburra.Australia is home to many dangerous animals including some of the most venomous snakes in the world. The dingo was introduced by Austronesian people who traded with Indigenous Australians around 3000 BCE.Many animal and plant species became extinct soon after first human settlement,including the Australian megafauna; others have disappeared since European settlement, among them the thylacine.