The Australian Aboriginal languages consist of up to twenty-seven language families and isolates, spoken by Aboriginal Australians of mainland Australia and a few nearby islands. The relationships between these languages are not clear at present. Despite this uncertainty the indigenous languages of Australia are collectively covered by the technical term "Australian languages". By convention, these do not include the Tasmanian languages or the eastern Torres Strait language Meriam Mer.
In the late 18th century, there were about 250 distinct Aboriginal social groupings, and a similar number of languages or varieties. At the start of the 21st century, fewer than 150 Aboriginal languages remain in daily use and all except only 13 are highly endangered. The surviving languages are located in the most isolated areas. For example, of the five least endangered Western Australian Aboriginal languages, four belong to the Ngaanyatjarra grouping of the Central and Great Victoria Desert. Yolŋu languages from north-east Arnhem Land are also currently learned by children. Bilingual education is being used successfully in some communities. Seven of the most widely spoken Australian languages, such as Warlpiri and Tiwi, retain between 1,000 and 3,000 speakers. Some Aboriginal communities and linguists show support for learning programs either for language revival proper or for only "post-vernacular maintenance" (teaching Indigenous Australians some words and concepts related to the lost language).
Aboriginal Tasmanians were nearly eradicated early in Australia's colonial history, and their languages were lost before much was recorded. Tasmania was separated from the mainland at the end of the Quaternary glaciation, and Tasmanian Aboriginal people apparently remained isolated from the outside world for around 10,000 years. Too little is known of their languages for classification, though they seem to have had phonological similarities with languages of the mainland.