The history of the First World War (WWI) reflects major transformations in a global context, influencing politics, economics, and society throughout the world. This conflict, which lasted from 1914 to 1918, involved many countries and killed millions of people. One of the main causes of WWI was the political alliances that were formed, including the Triple Entente (France, Russia, and Britain) and the Central Alliance (Germany, Austria-Hungary, and Italy). Rising tensions in Europe, coupled with the assassination of Archduke Franz Ferdinand, were the immediate trigger. This war not only brought significant human losses; however, its impact is much broader. On the political front, many empires collapsed, including the German, Austro-Hungarian, and Ottoman Empires. This paved the way for the formation of new countries and sparked a wave of nationalism in various parts of the world. In addition, the 1919 Treaty of Versailles that ended the war created discontent in Germany, becoming one of the causes of the rise of ideological extremism and the Second World War. From an economic perspective, WWI caused a deep recession for many countries. Mounting war costs and damaged infrastructure resulted in a large national debt. Changes in industry, especially in weapons production and technology, encouraged innovation but also led to high unemployment after the war ended. Socially, this war changed gender roles with women entering previously male-dominated employment sectors, creating momentum for the women’s voting rights movement. Additionally, the trauma experienced by returning troops, known as “shell shock,” is raising awareness about mental health. The legacy of WWI remains relevant today. The geopolitical consequences established during these conflicts, such as new state boundaries and shifts in power, still play a role in international relations today. The generation born from the effects of this war witnessed dramatic social change, giving rise to artistic and cultural movements that responded to the experience of war, such as Dada and Surrealism. Overall, the historical impact and legacy of the First World War created the foundation for many events in the 20th and 21st centuries. From the challenges of nationalism to mental health issues, the power of diplomacy to tensions between countries, a deep understanding of WWI is essential for analyzing current global conditions.