The European Union formally existed starting in 1993, when the Maastricht Treaty came into effect. This treaty marked a significant step toward deeper integration among European nations, establishing the EU's foundational structure and creating a single market. The Maastricht Treaty also introduced the concept of European citizenship, allowing citizens to reside and move freely within member states. The groundwork laid by this treaty has facilitated economic, political, and social collaboration, making the EU a major influence in global affairs. Over the years, the union has expanded, incorporating numerous countries and solidifying its role in promoting peace and stability in Europe.