While English is the de facto national language, 22.3% of Australians (5.8M people) spoke a language other than English at home in the 2021 Census. Top 10:
Indigenous languages: ~150 still spoken; ~50,000 speakers total. Top: Kriol, Yumplatok (Torres Strait Creole), Djambarrpuyŋu, Pitjantjatjara, Warlpiri. Many endangered; revival programs active.
Australia's linguistic diversity reflects post-WWII European migration, recent Asian migration, and the world's oldest continuous cultures.