The Iron Curtain was a term popularized by Winston Churchill to describe the ideological and physical division that separated Western Europe from Eastern Europe during the Cold War. It symbolized the boundary between the democratic nations aligned with the United States and the communist countries under Soviet influence. The Iron Curtain was significant as it represented the heightened tensions and mutual suspicions between these opposing superpowers. It also led to military alliances, propaganda efforts, and significant geopolitical changes, setting the stage for various conflicts and the eventual thawing of relations in the late 20th century.