Yugoslavia (/ˌjuːɡoʊˈslɑːviə/; lit. 'Land of the South Slavs') was a country in Central Europe and the Balkans that existed from 1918 to 1992. It came into existence following World War I, under the name of the Kingdom of Serbs, Croats and Slovenes from the merger of the Kingdom of Serbia with the provisional State of Slovenes, Croats and Serbs, and constituted the first union of South Slavic peoples as a sovereign state, following centuries of foreign rule over the region under the Ottoman Empire and the Habsburg monarchy.

Under the rule of the House of Karađorđević, the kingdom gained international recognition on 13 July 1922 at the Conference of Ambassadors in Paris and was renamed the Kingdom of Yugoslavia on 3 October 1929. Peter I was the country's first sovereign. Upon his father's death in 1921, Alexander I went on to rule the country through an extended period of political crisis that culminated in the 6 January Dictatorship and, ultimately, his assassination in 1934. Prince Paul headed the state as a prince regent until Alexander's son Peter II was declared of-age, which happened following the Yugoslav coup d'état in March 1941. Alexander I was the longest reigning of the three Yugoslav monarchs.

The kingdom was invaded and occupied by the Axis powers in April 1941, marking the start of World War II in Yugoslavia. The Communist-led Partisan resistance went on to proclaim the Democratic Federal Yugoslavia and acquire the backing of the Allies at the Tehran Conference in late November 1943. In 1944, King Peter II, then living in exile, gave his recognition to the Anti-Fascist Council for the National Liberation of Yugoslavia as the legitimate government. In November 1945, after the war ended, the regency council appointed by the King called a parliamentary election that established the Constituent Assembly of Yugoslavia. The Constituent Assembly proclaimed Yugoslavia a federal republic on 29 November 1945, thus abolishing monarchical rule. This marked the onset of a four-decade long uncontested communist party rule of the country. The newly proclaimed Federal People's Republic of Yugoslavia acquired the territories of Istria, Rijeka, and Zadar from Italy. Partisan leader Josip Broz Tito ruled the country from 1944 until his death in 1980, first as the prime minister and later as the president. In 1963, the country was renamed for the final time, as the Socialist Federal Republic of Yugoslavia (SFRY).

The six constituent republics that made up the SFRY were the socialist republics of Bosnia and Herzegovina, Croatia, Macedonia, Montenegro, Serbia, and Slovenia. Within Serbia were the two socialist autonomous provinces, Kosovo and Vojvodina, which, following the adoption of the 1974 Yugoslav Constitution, were largely equal to the other members of the federation. After an economic and political crisis and the rise of nationalism and ethnic conflicts following Tito's death, Yugoslavia broke up along its republics' borders during the Revolutions of 1989, at first into five countries, leading to the Yugoslav Wars. From 1993 to 2017, the International Criminal Tribunal for the former Yugoslavia tried political and military leaders from the former Yugoslavia for war crimes, genocide, and other crimes committed during those wars.

After the breakup, the republics of Montenegro and Serbia formed a reduced federative state, the Federal Republic of Yugoslavia (FRY). This state aspired to the status of sole legal successor to the SFRY, but those claims were opposed by the other former republics. Eventually, it accepted the opinion of the Badinter Arbitration Committee about shared succession and in 2003, its official name was changed to the State Union of Serbia and Montenegro. This state dissolved when Montenegro and Serbia each became independent states in 2006, with Kosovo having an ongoing dispute over its declaration of independence in 2008.

The concept of Yugoslavia, as a common state for all South Slavic peoples, emerged in the late 17th century and gained prominence through the Illyrian Movement of the 19th century. The name was created by the combination of the Slavic words jug ("south") and Slaveni/Sloveni (Slavs) and was in use as early as 1922 onward.^{[original research?]} Moves towards the formal creation of Yugoslavia accelerated after the 1917 Corfu Declaration between the Yugoslav Committee and the government of the Kingdom of Serbia.

The country was formed in 1918 immediately after World War I as the Kingdom of Serbs, Croats and Slovenes by union of the State of Slovenes, Croats and Serbs and the Kingdom of Serbia. It was commonly referred to at the time as a "Versailles state". Later, King Alexander I renamed the country Yugoslavia in 1929.

On 20 June 1928, Serb deputy Puniša Račić shot at five members of the opposition Croatian Peasant Party in the National Assembly, resulting in the death of two deputies on the spot and that of leader Stjepan Radić a few weeks later. On 6 January 1929, King Alexander I got rid of the constitution, banned national political parties, assumed executive power, and renamed the country Yugoslavia. He hoped to curb separatist tendencies and mitigate nationalist passions. He imposed a new constitution and relinquished his dictatorship in 1931. However, Alexander's policies later encountered opposition from other European powers stemming from developments in Italy and Germany, where Fascists and Nazis rose to power, and the Soviet Union, where Joseph Stalin became absolute ruler. None of these three regimes favored the policy pursued by Alexander I. In fact, Italy and Germany wanted to revise the international treaties signed after World War I, and the Soviets were determined to regain their positions in Europe and pursue a more active international policy.