World War I, which occurred from July 28, 1914 to November 11, 1918, was a global conflict involving many countries around the world, especially in Europe. The war became known as the “Great War” because of its scale and impact, changing the global political, social and economic map. The main cause of World War I was a complex system of alliances between European countries. Two main alliances emerged: the Allies, consisting of France, Britain, Russia, and then the United States; and the Central Empire, consisting of Germany, Austria-Hungary, and Italy (which later changed sides). Tensions rose after the assassination of Archduke Franz Ferdinand of Austria on June 28, 1914, triggering a series of events that led to war. The war was characterized by fierce fighting, trench warfare, and the use of new technology such as machine guns, airplanes, and poison gas. One of the most famous battles was the Battle of the Somme in 1916, which resulted in huge casualties. During this battle, more than a million people lost their lives in a futile attempt to seize several kilometers of land. The social impact of this war was also extraordinary. Millions of men were drafted to fight, while women took over roles in industry and other fields, changing gender norms and women’s rights. The war economy caused inflation and shortages of basic goods in many countries, especially in Germany and Russia. Russia, after facing heavy battlefield losses and social discontent, experienced a Revolution in 1917, which resulted in its withdrawal from the war. The Treaty of Brest-Litovsk was signed in March 1918, which gave Germany a major victory but changed the dynamics of the conflict as a whole. In 1918, with the entry of the United States into the conflict in 1917 and the increase in the number of Allied troops, the Central Empire began to experience defeat. Final attacks, such as the Meuse-Argonne Offensive, prompted Germany to surrender on November 11, 1918, ending the war. World War I resulted in major changes in the world order. The Treaty of Versailles in 1919 officially ended the war, established heavy sanctions against Germany, and established the League of Nations, the first attempt to create a more stable global peace. The map of Europe also changed, with the emergence of new states and the dissolution of empires. The legacy of World War I is profound, fueling subsequent conflicts, including World War II, and shaping modern geopolitics. This war demonstrated the brutal impact of modern technology in military conflict, as well as the importance of diplomacy in maintaining peace in an interconnected world.