An endangered language is a language that is at risk of falling out of use, generally because it has few surviving speakers.

If it loses all of its native speakers, it becomes a dead language.

The United Nations Educational, Scientific and Cultural Organization defines five levels of language endangerment between "safe" (not endangered) and "extinct":[1] The list below includes the findings from the third edition of Atlas of the World's Languages in Danger (2010; formerly the Red Book of Endangered Languages), as well as the online edition of the aforementioned publication, both published by UNESCO.

[2] (Note: Taiwan area is not included in the list above.

Related information is in section Taiwan.)