The "Free World" is a propaganda term, primarily used during the Second World War and Cold War, to refer to the Allies, Western Bloc and aligned countries.
During the Second World War, the term was primarily used against fascist states. During the Cold War, the term referred more broadly to all liberal democracies collectively, as opposed to communist states. It has traditionally primarily been used to refer to the countries allied and aligned with the United States, the European Union, and NATO. The term "leader of the free world" has been used to imply a symbolic and moral leadership, and was mostly used during the Cold War in reference to the president of the United States.