How communism begin in europe?
It all began when Karl Marx wrote his famous ideas opposing capitalism, using different terminology to label people and events that took place in capitalism in the 19th century. Basically, communism formed out of Marx's ideas against capitalism and he inadvertently created a system under that basic resistance. He believe that socialism, a system where common people owned the means of production, would eventually evolve into a classless system where there was no such thing as property rights and a system where people would assume the common identity, called communism. Long story short (because the evolution of communism is a VERY long story), in 1917, present day Russia, Vladamir Lenin took the ideas of Marxism and put them into practice after the Russian Revolution and after he took power in the newly formulated Soviet Union, initially called Leninism. Later down the road in the 1950's, Joesph Stalin committed to expanding the marxist ideology and began the Cold War. With the USSR's strengthening sphere of influence, they were able to divide Eastern Europe from the Western World under a political agreement known as Warsaw Pact and an economic agreement known as COMECON, whereas Western Europe followed the US-led plan, known as the Marshall Plan. The Warsaw Pact and COMECON let the USSR move into countries and develop them economically and politically, resulting in many Eastern European states turning into Marxist states. While this was happening, the USSR was also expanding Marxist ideals in Asia, creating the PRC (present day China), the DPRK (North Korea), and many states nearby the USSR. Once the Soviet Union collapsed and dissolved itself, Communism did not continue to spread. The only true stronghold of communist ideals, which actually isn't really a communist country, but more of a totalitarian regime, would be North Korea. The PRC existed after the Soviet collapse, but evolved into a State-sponsored Capitalist system.
What does "communist" mean ?
A silly ideal that the state (country) should provide everything for everyone. Mostly since no one is rewarded for working harder under this system, it's been a miserable failure everywhere it's been practiced - leaving dwindling standards of living in its wake.
What would a communist America look like?
Well a nation cannot be communist. Communism has to be worldwide. However, a nation can have true socialism, which is what the USSR or PRC had earlier. So let's talk about what a really socialist America would look like. First of all, the rich in America would be stripped of most of their rights. Everyone would have to leave their mansions and make way for the homeless. Food, education, healthcare etc. would be free. Racism would be countered effectively and there would be more interracial marriages. Sexual minorities would be more open about their orientation. The country would stop using cheap raw material and labour from the third world. All jobs would remain at home and there would be 100% employment. Whole of the economy would be nationalized and the workers would control the workplaces through democratic decisions among themselves. People from all over the world would be free to immigrate to the USA. This would include political exiles, revolutionaries etc. The government would be a direct democratic government, with no elites. People would form local councils through votes as often as required, with a maximum gap of four years. The cops would be replaced by the whole population taking turns to do the policing. Everyone would also take turns for administrative duties, thus making the government truly belong to the people. Lastly, USA would be fighting all the capitalist countries and helping communists worldwide. So, there would be a flow of communists, soldiers and arms to other countries, fighting their oppressive governments.