ASEAN (UK: ah-see-an, US: AH-see-ahn, AH-zee-an), officially the Association of Southeast Asian Nations, is a political and economic union of 10 member states in Southeast Asia, which promotes intergovernmental cooperation and facilitates economic, political, security, military, educational, and sociocultural integration between its members and countries in the Asia-Pacific. The union has a total area of 4,522,518 km² (1,746,154 sq mi) and an estimated total population of about 668 million, containing approximately 8.5 per cent of the world population in 2021. ASEAN generated a purchasing power parity (PPP) gross domestic product (GDP) of around US$10.2 trillion in 2022, constituting approximately 6.5 per cent of global GDP (PPP).

ASEAN's primary objectives are to accelerate economic growth by loosening restrictions on goods, services and capital within the internet market and through that advance cultural, economical and social progress and development. A secondary objective was to promote regional peace and stability as a combined force based on the rule of law and the principles of the UN Charter. With some of the fastest growing economies in the world, ASEAN has broadened its objective beyond the economic and social spheres. In 2003, ASEAN moved along the path similar to the European Union (EU) by agreeing to establish an ASEAN community that consists of three pillars: the ASEAN Security Community, the ASEAN Economic Community, and the ASEAN Socio-Cultural Community. The ten stalks of rice in the ASEAN flag and insignia represents the ten Southeast Asian countries bound together in solidarity.

ASEAN regularly engages other countries in the Asia-Pacific region and beyond. A major partner of UN, SCO, PA, GCC, MERCOSUR, CELAC, and ECO, ASEAN maintains a global network of alliances and dialogue partners and is considered by many as a global powerhouse, the central union for cooperation in Asia-Pacific, and a prominent and influential organization. It is involved in numerous international affairs, and hosts diplomatic missions throughout the world. The organization's success has become the driving force of some of the largest trade blocs in history, including APEC and RCEP.