World War I lasted from 1914 to 1918, changing the world order significantly. A variety of complex causes led the world into this great conflict. One of the main causes is the overflowing nationalism in Europe. Nations such as Germany, France and England competed to show their national glory. For example, tensions between Germany and France escalated after the Franco-Prussian War (1870-1871), which resulted in the loss of Alsace-Lorraine to France. In addition, complicated military alliances also worsened the situation. There were two main blocs: the Triple Entente (England, France, and Russia) and the Triple Alliance (Germany, Austria-Hungary, and Italy). When conflict broke out in the Balkans, this alliance sparked the involvement of major powers in a broader scenario. The assassination of Prince Ferdinand of Austria on 28 June 1914 marked the immediate trigger that triggered this mechanism. Imperialism is also the main trigger. European countries vied for colonial control in Africa and Asia, creating sharp rivalries. The economic reasons behind imperialism deepen the gaps between countries, which in turn increases tensions. The impact of World War I was felt throughout the world. In Europe, this conflict caused millions of deaths and massive destruction. The infrastructure, economy, and society of many countries were destroyed. The 1919 Treaty of Versailles demanded reparation payments from Germany, leading to prolonged economic suffering. The social impact is also no less significant. The war had changed gender roles, with many women entering the workforce to replace the men who had entered the war. This became the beginning of the movement for women’s voting rights in various countries. Politically, the emergence of new states, such as Czechoslovakia and the Kingdom of Yugoslavia, reshaped the map of Europe. The Bolshevik Revolution in Russia was another significant result, changing the government system and ideological perspective at that time. Not only in Europe, the global impact is also felt. Economic instability brought about a global crisis in the late 1920s, which contributed to the emergence of the Great Depression. Anti-war sentiment and rejection of existing systems of government fueled extremist movements around the world, including the rise of totalitarianism in Germany and Italy. In a cultural context, World War I sparked an explosion in literature and art. Many writers and artists began to depict the cruelty and absurdity of the war’s legacy; As a result, new trends emerged in modern literature and art. Understanding the causes and effects of World War I helps explain many of the problems that society still faces today. By studying this history, efforts to create peace and social justice become more relevant. This war is not just a historical note, but is a reminder that international tensions need to be resolved before they develop into large-scale conflict.