Azerbaijani (ˌæzərbaɪˈdʒæni,_-ɑːni ) or Azeri (æˈzɛəri,_ɑː-,_ə- ), also referred to as Azeri Turkic or Azeri Turkish, is a Turkic language from the Oghuz sub-branch spoken primarily by the Azerbaijani people, who live mainly in the Republic of Azerbaijan where the North Azerbaijani variety is spoken, and in the Azerbaijan region of Iran, where the South Azerbaijani variety is spoken. Although there is a very high degree of mutual intelligibility between both forms of Azerbaijani, there are significant differences in phonology, lexicon, morphology, syntax, and sources of loanwords.
North Azerbaijani has official status in the Republic of Azerbaijan and Dagestan (a federal subject of Russia), but South Azerbaijani does not have official status in Iran, where the majority of Azerbaijani people live. It is also spoken to lesser varying degrees in Azerbaijani communities of Georgia and Turkey and by diaspora communities, primarily in Europe and North America.
Both Azerbaijani varieties are members of the Oghuz branch of the Turkic languages. The standardized form of North Azerbaijani (spoken in the Republic of Azerbaijan and Russia) is based on the Shirvani dialect, while South Azerbaijani uses the Tabrizi dialect as its prestige variety. Since the Republic of Azerbaijan's independence from the Soviet Union in 1991, Northern Azerbaijani uses the Latin script. South Azerbaijani, on the other hand, has always used and continues to use the Perso-Arabic script. Azerbaijani language is closely related to Gagauz, Qashqai, Crimean Tatar, Turkish, and Turkmen, sharing varying degrees of mutual intelligibility with each of those languages.
Historically the language was referred by its native speakers as türk dili or türkcə, meaning either "Turkish" or "Turkic". After the establishment of the Azerbaijan SSR, on the order of Soviet leader Joseph Stalin, the "name of the formal language" of the Azerbaijan SSR was changed from "Turkish" to "Azerbaijani". The language is usually referred to as Turki or Torki in Iranian Azerbaijan.