The term denoted the ideological and physical boundary dividing Europe into two separate areas from the end of World War II until the end of the Cold War, roughly from 1945 to 1991. On one side were the Soviet-aligned Eastern Bloc countries, and on the other were the Western European nations allied with the United States. This division was characterized by restricted travel, communication, and economic exchange between the two blocs, and symbolized the efforts by the Soviet Union to block itself and its satellite states from open contact with the West. The phrase was popularized by Winston Churchill in a 1946 speech.
The concept is crucial for understanding the geopolitical landscape of the Cold War. It illuminates the tension and competition between the superpowers, the suppression of dissent in Eastern Europe, and the formation of alliances such as NATO and the Warsaw Pact. The existence of this division shaped diplomatic relations, military strategy, and cultural exchange during this era. Further, it represents the tangible manifestation of differing ideologies and power structures that defined the post-war world.