Azerbaijan (UK: (listen), US: ; Azerbaijani: Azərbaycan, [ɑːzæɾbɑjˈdʒɑn]), officially the Republic of Azerbaijan, is a transcontinental country located at the boundary of Eastern Europe and Western Asia. It is a part of the South Caucasus region and is bounded by the Caspian Sea to the east, Russia (Republic of Dagestan) to the north, Georgia to the northwest, Armenia and Turkey to the west, and Iran to the south. Baku is the capital and largest city.

The Azerbaijan Democratic Republic proclaimed its independence from the Transcaucasian Democratic Federative Republic in 1918 and became the first secular democratic Muslim-majority state. In 1920, the country was incorporated into the Soviet Union as the Azerbaijan SSR. The modern Republic of Azerbaijan proclaimed its independence on 30 August 1991, shortly before the dissolution of the Soviet Union in the same year. In September 1991, the ethnic Armenian majority of the Nagorno-Karabakh region formed the self-proclaimed Republic of Artsakh. The region and seven surrounding districts are internationally recognized as part of Azerbaijan, pending a solution to the status of Nagorno-Karabakh through negotiations facilitated by the OSCE, although became de facto independent with the end of the First Nagorno-Karabakh War in 1994. Following the Second Nagorno-Karabakh War in 2020, the seven districts and parts of Nagorno-Karabakh were returned to Azerbaijani control.

Azerbaijan is a unitary semi-presidential republic. It is one of six independent Turkic states and an active member of the Organization of Turkic States and the TÜRKSOY community. Azerbaijan has diplomatic relations with 182 countries and holds membership in 38 international organizations, including the United Nations, the Council of Europe, the Non-Aligned Movement, the OSCE, and the NATO PfP program. It is one of the founding members of GUAM, the CIS, and the OPCW. Azerbaijan is also an observer state of the WTO.

The vast majority of the country's population (97%) is nominally Muslim, but the constitution does not declare an official religion and all major political forces in the country are secularist. Azerbaijan is a developing country and ranks 91st on the Human Development Index. It has a high rate of economic development, literacy, and a low rate of unemployment. However, the ruling New Azerbaijan Party, in power since 1993, has been accused of authoritarian leadership under the leadership of both Heydar Aliyev and his son Ilham Aliyev, and deteriorating the country's human rights record, including increasing restrictions on civil liberties, particularly on press freedom and political repression.