Western Australia is a state occupying the western 33 percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, and the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Australia is Australia's largest state, with a total land area of 2,527,013 square kilometres. As of 2021, the state has about 2.68 million inhabitants.
Western Australia is home to around 630 species of birds, Of these around 15 are endemic to the state. The best areas for birds are the southwestern corner of the state and the area around Broome and the Kimberley.
The Flora of Western Australia comprises 10,162 published native vascular plant species, along with a further 1,196 species currently recognised but unpublished. They occur within 1,543 genera from 211 families; there are also 1,276 naturalised alien or invasive plant species, more commonly known as weeds. In the southwest region are some of the largest numbers of plant species for its area in the world.
Western Australia's ecoregions include the sandstone gorges of The Kimberley on the northern coast, and below that the drier Victoria Plains tropical savanna inland, and the semi-desert Pilbara shrublands, Carnarvon xeric shrublands, and Western Australian mulga shrublands to the southwest. Southwards along the coast are the Southwest Australia savanna and the Swan Coastal Plain around Perth, with the jarrah-karri forest and shrublands on the southwest corner of the coast around the Margaret River wine-growing area. Going east along the Southern Ocean coast is the Goldfields-Esperance region, including the Esperance mallee and the Coolgardie woodlands inland around town of Coolgardie. Deserts occupy the interior, including the Great Sandy-Tanami desert, Gibson Desert, Great Victoria Desert, and Nullarbor Plain.