Covering an incredible area of Australia – 5.6 million square km or 2.1 square miles, an incredible 73% of the countries area, while there are many other parts of Australia to visit, the outback defines it.
This entire area is classed as either arid (up to 250mm) or semi-arid (250-350mm) of rainfall. Given this, all the animals here are adapted to need as little water as possible. This compares with the Sahara, which has around 75mm of rain, and the Kalahari which gets 250-300mm per year.
What this says, is that this place gets little rain.
This is the same with the wildlife that lives here, which can survive with little water.