World War I reshaped the global landscape from 1914 to 1918. Major powers clashed in a conflict sparked by nationalism, imperialism, and complex alliances. The war introduced new technologies and tactics, from trench warfare to tanks and aircraft. The conflict's aftermath brought profound changes. Empires crumbled, new nations emerged, and the League of Nations was formed. Economic turmoil and political instability set the stage for future conflicts, while society grappled with the war's immense human toll.