Dagestan (ˌdæɡᵻˈstæn,_-ˈstɑːn ; Дагестан; dəɡjɪˈstan), officially the Republic of Dagestan, is a republic of Russia situated in the North Caucasus of Eastern Europe, along the Caspian Sea. It is located north of the Greater Caucasus, and is a part of the North Caucasian Federal District. The republic is the southernmost tip of Russia, sharing land borders with the countries of Azerbaijan and Georgia to the south and southwest, the Russian republics of Chechnya and Kalmykia to the west and north, and with Stavropol Krai to the northwest. Makhachkala is the republic's capital and largest city; other major cities are Derbent, Kizlyar, Izberbash, Kaspiysk, and Buynaksk.
Dagestan covers an area of , with a population of over 3.1 million, consisting of over 30 ethnic groups and 81 nationalities. With 14 official languages, and 12 ethnic groups each constituting more than 1% of its total population, the republic is one of Russia's most linguistically and ethnically diverse, and one of the most heterogeneous administrative divisions in the world. Most of the residents speak one of the Northeast Caucasian, or Turkic, languages; however, Russian is the primary language and the lingua franca in the republic.
The word Dagestan is of Turkish and Persian origin, directly translating to "Land of the Mountains". The Turkish word dağ means "mountain", and the Persian suffix -stan means "land".
Some areas of Dagestan were known as Lekia, Avaria and Tarki at various times.
Between 1860 and 1920, Dagestan was referred to as Dagestan Oblast, corresponding to the southeastern part of the present-day republic. The current borders were created with the establishment of the Dagestan Autonomous Soviet Socialist Republic in 1921, with the incorporation of the eastern part of Terek Oblast, which is not mountainous but includes the Terek littoral at the southern end of the Caspian Depression.