NATO, or the North Atlantic Treaty Organization, is a military alliance formed in 1949. It was created to provide collective defense against potential threats, particularly during the Cold War. Member countries agree that an attack on one is an attack on all, promoting security and cooperation among its members. The alliance originally included 12 countries, but has since expanded to 31 members as of 2023. NATO conducts various missions, including crisis management and cooperative security, and works to promote democratic values and stability in the Euro-Atlantic area.