The Revolutions of 1989, also known as the Fall of Communism, was a revolutionary wave of liberal democracy movements that resulted in the collapse of most Marxist–Leninist governments in the Eastern Bloc and other parts of the world. Sometimes this revolutionary wave is also called the Fall of Nations or the Autumn of Nations, a play on the term Spring of Nations that is sometimes used to describe the Revolutions of 1848 in Europe. It may have contributed to the eventual dissolution of the Soviet Union—the world's largest Marxist–Leninist state—and the abandonment of communist regimes in many parts of the world, some of which were violently overthrown. The events, especially the fall of the Soviet Union, drastically altered the world's balance of power, marking the end of the Cold War and the beginning of the post-Cold War era.

A communist state, also known as a Marxist–Leninist state, is a one-party state that is administered and governed by a communist party guided by Marxism–Leninism. Marxism–Leninism was the state ideology of the Soviet Union, the Comintern after Bolshevisation and the communist states within the Comecon, the Eastern Bloc, and the Warsaw Pact. Marxism–Leninism currently still remains the ideology of a few parties around the world. After its peak when many communist states were established, the Revolutions of 1989 brought down most of the communist states, however, it is still the official ideology of the ruling parties of China, Cuba, Laos, Vietnam, and to a lesser extent, North Korea. During most of the 20th century, before the Revolutions of 1989, around one-third of the world's population lived under communist states.