The term "Iron Curtain" refers to the ideological and physical boundary that separated Western Europe, aligned with NATO and liberal democracies, from Eastern Europe, under the influence of the Soviet Union and communist regimes during the Cold War. This metaphor was popularized by Winston Churchill in 1946, highlighting the stark division in post-World War II Europe. The Iron Curtain symbolized the struggle between capitalism and communism, leading to political tensions, military conflicts, and the establishment of two opposing blocs in the global geopolitical landscape, influencing international relations throughout the 20th century.