Denmark (Danish: Danmark, pronounced [ˈtænmɑk] (listen)) is a Nordic country in Northern Europe. It is the metropolitan part of and most populous constituent of the Kingdom of Denmark, a constitutionally unitary state that includes the autonomous territories of the Faroe Islands and Greenland in the North Atlantic Ocean. Metropolitan Denmark is the southernmost of the Scandinavian countries, lying south-west and south (Bornholm and Ertholmene) of Sweden, south of Norway, and north of Germany, with which it shares a short and only land border.

As of 2013, the Kingdom of Denmark, including the Faroe Islands and Greenland, has a total of 1,419 islands above 100 square metres (1,100 sq ft); 443 of which have been named and of which 78 are inhabited. Spanning a total area of 42,943 km² (16,580 sq mi), metropolitan Denmark consists of the northern part of the Jutland peninsula and an archipelago of 406 islands. Of these, the most populated island is Zealand, on which the capital Copenhagen is situated, followed by Funen, the North Jutlandic Island, and Amager. Denmark's geography is characterised by flat, arable land, sandy coasts, low elevation, and a temperate climate. It had a population of 5.935 million (1 February 2023), of which 800,000 (2 million in the wider area) live in the capital and largest city, Copenhagen. Denmark exercises hegemonic influence in the Danish Realm, devolving powers to handle internal affairs. Home rule was established in the Faroe Islands in 1948 and in Greenland in 1979; the latter obtained further autonomy in 2009.

The unified Kingdom of Denmark emerged in the eighth century as a proficient maritime power amid the struggle for control of the Baltic Sea. In 1397, it joined Norway and Sweden to form the Kalmar Union, which persisted until the latter's secession in 1523. The remaining Kingdom of Denmark–Norway endured a series of wars in the 17th century that resulted in further territorial cessions to the Swedish Empire. Following the Napoleonic Wars, Norway was absorbed into Sweden, leaving Denmark with the Faroe Islands, Greenland, and Iceland. A surge of nationalist movements in the 19th century were defeated in the First Schleswig War of 1848, though the Second Schleswig War of 1864 resulted in further territorial losses to Prussia. The period saw the adoption of the Constitution of Denmark on 5 June 1849, ending the absolute monarchy that was established in 1660 and introducing the current parliamentary system.

An industrialised exporter of agricultural produce in the second half of the 19th century, Denmark introduced social and labour-market reforms in the early 20th century, which formed the basis for the present welfare state model and advanced mixed economy. Denmark remained neutral during World War I but regained the northern half of Schleswig in 1920. Danish neutrality was violated in World War II following a swift German invasion in April 1940. During occupation, a resistance movement emerged in 1943 while Iceland declared independence in 1944; Denmark was liberated in May 1945. Soviet forces left Bornholm 5 April 1946. In 1973, Denmark, together with Greenland but not the Faroes, became a member of what is now the European Union, but negotiated certain opt-outs, such as retaining its own currency, the krone.

Denmark is a developed country with a high standard of living. Denmark is a founding member of NATO, the Nordic Council, the OECD, OSCE, and the United Nations; it is also part of the Schengen Area. Denmark maintains close political, cultural, and linguistic ties with its Scandinavian neighbours, with the Danish language being partially mutually intelligible with both Norwegian and Swedish.