The main idea behind the Marshall Plan, officially known as the European Recovery Program, was to provide economic assistance to rebuild European economies after World War II. Introduced by U.S. Secretary of State George Marshall in 1947, the plan aimed to prevent the spread of communism by stabilizing these nations through financial aid, fostering trade, and rebuilding infrastructure. The U.S. invested over $12 billion in various European countries, significantly contributing to the recovery and modernization of European nations, leading to economic stability and political cooperation during the Cold War era.