This is a very difficult question you have asked. To understand "communism' you would have to read Karl Marx for what the world has seen in terms of communist regimes has all been garbage to put it plainly. China tried, Vietnam tried, North Korea claims to be communist ... all failures though (there were many others as well).
The closest country that has come to achieve "the communist dream" has been Cuba but it did not have much luck either with the American Empire starving it of trade and isolating it. We shall have to watch Venezuela, Bolivia, El Salvador, all countries which are moving closer to a communist regime.
Socialist countries on the other hand are more common. Most of the European countries (especially the Nordic ones) have socialist systems of government which are a mixture of communism and capitalism.