The Second World is a term that was used during the Cold War to refer to the industrial socialist states that were under the influence of the Soviet Union. In the first two decades following World War II, 19 communist states emerged; all of these were at least originally within the Soviet sphere of influence, though some (notably, Yugoslavia and the People's Republic of China) broke with Moscow and developed their own path of socialism while retaining Communist governments. But most communist states remained part of this bloc until the fall of the Soviet Union in 1991; afterwards, only five Communist states remained: China, North Korea, Cuba, Laos, and Vietnam. Along with "First World" and "Third World", the term was used to divide the states of Earth into three broad categories.
The concept of "Second World" was a construct of the Cold War and the term is still largely used to describe former communist countries that are between poverty and prosperity, many of which are now capitalist states. Subsequently the actual meaning of the terms "First World", "Second World" and "Third World" changed from being based on political ideology to an economic definition. The three-world theory has been criticized as crude and relatively outdated for its nominal ordering (1; 2; 3) and sociologists have instead used the words "developed", "developing", and "underdeveloped" as replacement terms for global stratification (which in turn have been criticized as displaying a colonialist mindset)  —nevertheless, the three-world theory is still popular in contemporary literature and media. This might also cause semantic variation of the term between describing a region's political entities and its people.