Most Communist Parties arose in the 1920s as a result of a split among socialist parties over whether revolution was necessary to achieve their ends and whether the socialist parties should accept the leadership of the Communist Party of the Soviet Union. Parties which renounced revolution and the leadership of the CPSU became supporters of social democracy while parties which remained committed to revolution and CPSU leadership became communist parties.
During the period of Stalinist domination of world Communism (1929-1953), communist parties in many nations emulated a structure copied from the organisation of the Communist Party of the Soviet Union, known as democratic centralism. In theory a party congress would elect a central committee, which elected a Politburo. In practice, the Politburo was self perpetuating and tended to control the central committee which controlled the party congresses. In most nations where communist parties gained power, opposition parties were banned or assimilated into socialist united fronts.
Members of communist parties were persecuted in some countries in the early Cold War period, when anti-communist sentiment swept through much of the West following World War II. But in Italy and France large Communist Parties played a prominent part in politics through the post-war decades.
In the third world, communist parties became popular in some areas because they promised an overthrow of a governmental structure that many considered oppressive. However, the civil wars which resulted often became emeshed into the Cold War with usually the Soviet Union supported the Communist forces and the United States supporting the anti-communist ones.
Among the splits within Communist parties were the split between Stalin and Trotsky in the 1920's and then the split between the Soviet Union and the People's Republic of China in the early 1960's. (see Sino-Soviet split)
Communist parties gained strong electoral and organisational support in France and in Italy, where they and developed a variant ideology known as Eurocommunism. While these parties advocated radical restructuring of the economy, they also eventually accepted the legitimacy of multi-party elections.
Communists parties have had various fates after the collapse of the Berlin Wall. Many parties Eastern Europe and Italy have attempted, with varying degrees of success, to transform themselves into democratic leftist parties, often changing their many in the process. Examples of these parties are the Party of Democratic Socialism in Germany. In Russia, the Communist Party exists as an opposition force with declining membership.
Communist parties remain in power in the People's Republic of China. Cuba, and North Korea. In the case of the Communist Party of China, the party has reinterpreted Marxism to allow for economic reform and markets in the context of an authoritarian state. Cuba and North Korea however have remained organized along Stalinist lines.
The major Communist parties have mostly disappeared after the fall of the Soviet Union. The Italian Communist Party, for example, split in two, and the larger group became a democratic socialist party. But in many countries various parties still claim to be communist, each according to its own version of communism. There are still important Communist parties in France, Greece, Italy, Portugal, India, South Africa, Chile and Japan, though all are in decline.