Navajo (Diné bizaad) belongs to the Southern branch of the Athabaskan family, within the Na-Dené stock, and is closely related to Apache. Its speakers descend from Athabaskan peoples who migrated from northwestern Canada and Alaska into the North American Southwest, probably between the 14th and 16th centuries. As a result, Navajo retains structural features shared with northern Athabaskan languages despite the vast geographic distance.

The Navajo people (Diné) live primarily within the Navajo Nation, a large territory spanning parts of Arizona, New Mexico, and Utah in the southwestern United States. With roughly 150,000 speakers, Navajo is the most widely spoken Indigenous language north of Mexico, though intergenerational transmission has declined markedly. Traditional culture centers on the concept of hózhó (harmony and balance), matrilineal clan organization, and sheep herding.

Following contact with Spanish and later U.S. colonizers, the Navajo people endured the violent Long Walk (Hwéeldi) of 1864, when the U.S. Army forcibly deported them to Bosque Redondo. Decades later, during World War II, the famous Navajo Code Talkers used their language to create an unbreakable military code in the Pacific theater. This contribution proved decisive and stood in stark contrast to the boarding-school policies that punished children for speaking their language.

Although Navajo remains comparatively vigorous relative to other U.S. Indigenous languages, UNESCO classifies it as vulnerable to endangered owing to the decline of young speakers. Immersion schools exist, such as the Diné Language Immersion School in Fort Defiance, alongside university programs at Diné College and Navajo-language radio broadcasting. The language also enjoys media presence, with Navajo dubs of films such as Star Wars and Finding Nemo.