Azerbaijan holds 10,139,177 people as of 2023 United Nations data. Ethnic Azerbaijanis constitute 91.6 percent of the population according to the State Statistical Committee of Azerbaijan. Lezgins form the largest minority at 2 percent, concentrated in the northern districts bordering Dagestan. Russians comprise 1.3 percent, down from 7.2 percent in 1979 before the Soviet collapse triggered mass emigration. Talysh communities inhabit the southeast near Lankaran, though census figures remain disputed between official counts of 0.8 percent and Talysh advocacy claims exceeding 10 percent. Armenians numbered 390,505 in 1989 but nearly all departed during the Nagorno-Karabakh conflict, leaving fewer than 30,000 by 2009. Tats, Avars, Tatars, Ukrainians, and Georgians form smaller groups. Baku concentrates 2.3 million residents, making it six times larger than Ganja at 335,600. Sumqayit holds 341,200 people working primarily in petrochemical and aluminum industries established during Soviet industrialization drives of the 1950s.
Azerbaijani serves as the sole official language, spoken natively by 92.5 percent of citizens. The language belongs to the Oghuz branch of Turkic languages, sharing closer grammatical and lexical ties with Turkish than with Central Asian Turkic tongues. Russian functions as a lingua franca for 30 percent of the population, particularly among those educated before 1991 and in technical fields. Lezgin speakers use a Northeast Caucasian language unrelated to Turkic or Indo-European families. Talysh is a Northwestern Iranian language distinct from Persian. The Tat community speaks Judeo-Tat, another Iranian language written in Hebrew script by Jewish Tats and Cyrillic by Muslim Tats. Azerbaijan switched from Arabic script to Latin in 1929, then to Cyrillic in 1939 under Soviet mandate, then back to a modified Latin alphabet in 1991 which became compulsory for official documents in 2001.
Islam claims 96.9 percent adherence according to the State Committee for Work with Religious Organizations, though the Pew Research Center's 2012 study found only 21 percent pray daily and 54 percent say religion is very important in their lives. Shia Muslims form 55 to 65 percent of Muslims, concentrated in southern regions near the Iranian border and in Baku's traditional neighborhoods. Sunni Islam dominates in northern villages along the Dagestan border and in Nakhchivan. The split reflects historical influence zones, with Safavid Persia imposing Shia orthodoxy from 1501 while Ottoman territories maintained Sunni practice. Salafi movements gained followers in northern districts after 1991, prompting government crackdowns from 2015. Russian Orthodox Christians number approximately 280,000, almost entirely ethnic Russians and Ukrainians. Jews have lived continuously since the 5th century, with three distinct communities: Mountain Jews speaking Judeo-Tat, Georgian Jews, and Ashkenazi arrivals during the 19th century. The combined Jewish population fell from 40,000 in 1989 to roughly 8,000 by 2018 as emigration to Israel and the United States accelerated. Zoroastrians maintained fire temples until the 19th century. Ateshgah Fire Temple near Baku served Hindu and Zoroastrian traders until 1883 when natural gas pressure dropped and the eternal flame extinguished. Caucasian Albania, distinct from Balkan Albania, introduced Christianity in the 4th century, but Arab conquest from 639 to 643 initiated gradual Islamization completed by the 16th century. Albanian churches survive in Shaki and Qabala districts.