NATO stands for North Atlantic Treaty Organization. It is a political and military alliance that was formed in 1949 by the United States, Canada, and several Western European countries. The primary purpose of NATO is to provide collective defense and security for its member countries against potential external threats. The alliance was formed during the Cold War period, as a response to the perceived threat from the Soviet Union and its communist allies in Eastern Europe. NATO was intended to promote stability and security in the region and to deter any potential aggression from the Soviet Union. The alliance has evolved over time and remains an important security organization today.