Language isolates are languages that cannot be classified into larger language families. Basque in Europe, Ainu in Asia, Sandawe in Africa, and Haida in North America, are all examples of language isolates. The number of language isolates is unknown.
One explanation for the existence of language isolates is that they might be the last remaining branch of a larger language family. The language possibly had relatives in the past which have since disappeared without being documented. Another explanation for language isolates is that they developed in isolation from other languages. This explanation mostly applies to sign languages that have arisen independently of other spoken or signed languages.
Some languages once seen as isolates may be reclassified as small families if some of their dialects are judged to be sufficiently different from the standard to be seen as different languages. Examples include Japanese and Georgian: Japanese is now part of the Japonic language family with the Ryukyuan languages, and Georgian is the main language in the Kartvelian language family. There is a difference between language isolates and unclassified languages, but they can be difficult to differentiate when it comes to classifying extinct languages. If such efforts eventually do prove fruitful, a language previously considered an isolate may no longer be considered one, as happened with the Yanyuwa language of northern Australia, which has been placed in the Pama–Nyungan family. Since linguists do not always agree on whether a genetic relationship has been demonstrated, it is often disputed whether a language is an isolate.