Short answers, pulled from the story.
Yugoslavia existed from 1918 to 1992. It was founded immediately after World War I as the Kingdom of Serbs, Croats and Slovenes and dissolved during the Yugoslav Wars of the early 1990s, with its final successor states becoming independent between 1991 and 2006.
Josip Broz Tito was the leader of the Yugoslav Partisans during World War II and ruled Yugoslavia from 1944 until his death on the 4th of May 1980. He served first as prime minister and later as president, and was named President for life on the 7th of April 1963.
Yugoslavia's breakup resulted from a combination of economic collapse in the 1980s, the legacy of the 1974 constitution which created structural deadlock in federal decision-making, the rise of nationalist leaders including Slobodan Milosevic, and ethnic conflicts that escalated after Tito's death in 1980. Slovenia and Croatia declared independence on the 25th of June 1991, triggering a series of wars.
On the 6th of January 1929, King Alexander I abolished the Yugoslav constitution, banned political parties based on national identity, and assumed direct executive power. He also renamed the country Yugoslavia and redrew its internal borders into new provinces called banovinas, named after rivers, in an attempt to suppress separatist movements.
Germany, Italy, and Hungary invaded Yugoslavia at 5:12 a.m. on the 6th of April 1941, and Yugoslavia signed an armistice on the 17th of April after eleven days of resistance. More than 300,000 Yugoslav officers and soldiers were taken prisoner. The Ustaše regime in occupied Croatia murdered around 300,000 Serbs and at least 30,000 Jews and Roma between 1941 and 1945. Official Yugoslav post-war estimates counted 1,704,000 wartime dead; subsequent research placed the actual figure closer to 1 million.
Yugoslavia broke apart into seven internationally recognised states: Slovenia and Croatia (independent the 25th of June 1991), North Macedonia (the 8th of September 1991), Bosnia and Herzegovina (the 3rd of March 1992), and Montenegro and Serbia (both 5-the 6th of June 2006). Kosovo declared independence on the 17th of February 2008, a status that remains disputed; Kosovo is not a member of the United Nations.