What is the official language of Bhutan?

Dzongkha is the national language of Bhutan. The word "dzongkha" means the language (kha) spoken in the dzong "fortresses"—the fortress-like dzong architecture characterises monasteries established throughout Bhutan by its unifier, Ngawang Namgyal, 1st Zhabdrung Rinpoche, in the 17th century.

Dzongkha bears a close linguistic relationship to J'umowa, which is spoken in the Chumbi Valley of Southern Tibet, and to Sikkimese. It has a much more distant relationship to Standard Tibetan. Although spoken Dzongkha and Tibetan are largely mutually unintelligible, the literary forms of both are both highly influenced by the liturgical (clerical) Classical Tibetan language, known in Bhutan as Chöke, which has been used for centuries by Buddhist monks. Chöke was used as the language of education in Bhutan until the early 1960s when it was replaced by Dzongkha in public schools.