Dagestan ( DAG-i-STA(H)N; Russian: Дагеста́н; IPA: [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 50,300 square kilometres (19,400 square miles), 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.