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.

The term "Free World" emerged in the political discourse of the United States in May 1940, following Germany's attack on Belgium, the Netherlands, and France during World War II. It denoted all democracies that resisted authoritarian and world revolutionary states such as Germany, Italy, Japan, and the Soviet Union. In June 1941, U.S. President Franklin D. Roosevelt explicitly used the term when urging Congress to approve military aid. However, following the United States' entry alongside the Soviet Union in the war, Roosevelt used the term primarily in reference to the United Nations in opposition against Germany, Italy, and Japan.

In the years that followed the war, particularly during the Cold War, the "Free World" came to encompass a bloc of democracies, such as the United States and many Western European nations, along with their anti-communist but authoritarian allies. In 1950, U.S. Representative Daniel J. Flood commented "He^[who?] used the phrase 'free world' all the time—the free world, the free world, the free world. That impressed me very much vis-à-vis the Communist world, for instance. It is a tremendously good propaganda term. Is it being plugged enough?"

During the Cold War, many neutral countries—either those in what is considered the Third World, or those having no formal alliance with either the United States or the Soviet Union—viewed the claim of "Free World" leadership by the United States as grandiose and illegitimate.

While "Free World" had its origins in the Cold War, the phrase is still used after the end of the Cold War and during the Global War on Terrorism. Samuel P. Huntington said the term has been replaced by the concept of the international community, which, he argued, "has become the euphemistic collective noun (replacing "the Free World") to give global legitimacy to actions reflecting the interests of the United States and other Western powers."

The "Leader of the Free World" was a colloquialism, first used during the Cold War, to describe either the United States or, more commonly, the president of the United States. The term when used in this context suggested that the United States was the principal democratic superpower, and the U.S. president was by extension the leader of the world's democratic states, i.e. the "Free World".

But remember, we have differences with our allies all over the world. They are family differences, and sometimes they are acute, but, by and large, the reason we call it "free world" is because each nation in it wants to remain independent under its own government and not under some dictatorial form of government.