Explanation and Background of Socialism and Marxism
Socialism and Communism are more accurately called economic and social systems rather than political systems.  However, the real world application of the economics behind socialism and communism requires a particular form of government able to support it.

Early socialists wanted to create self-sufficient communities where everyone owned everything together, and where no one was left in need of anything. In other words, all property and work was shared for the benefit of the entire community. Socialists believed that if there was no money and everyone's needs were met, war and fighting would stop.

Marxist Socialism

In 1848, Karl Marx, a German living in London, England, and Friedrich Engels wrote The Communist Manifesto to explain their ideas.  In it, Marx and Engels claimed that all of history was a continuous struggle between people who had material goods and wealth, and people who did not have any (the "haves" vs. the "have nots").  They also said that capitalism, an economic system in which factories and businesses are owned by private individuals or corporations, took advantage of the working class, and, therefore, should be abolished.

Marx and Engels believed that all over Europe the working class, the proletariat,  would overthrow the capitalist system and form their own governments in response to capitalist abuses.  Further, they thought that such governments would create a classless society in which all wealth and power would be shared equally among all people.  

The Communist Revolution, as predicted by Marx and Engels, did not occur.  What neither man had considered, was that nationalism, a feeling of intense pride and devotion to one's country, was even stronger than the desire to be free from capitalist oppression.

Communist Successes

The Union of Soviet Socialist Republics (U.S.S.R.) / Soviet Union

Ironically, the first time Communists successfully overthrew an established government, it was not even a capitalist one.  In Russia, in 1917, V.I. Lenin and Leon Trotsky led a group of socialist revolutionaries called Bolsheviks, in a coup against Czar Nicholas II.  Lenin promised the people "peace, land and bread," but used secret police and brutality to create a one-party government where the Communist Party, and not the people, had the ultimate power.

Lenin's successor, Josef Stalin, turned Russia, now called the Soviet Union, into a totalitarian state.  Every aspect of people's lives was controlled by the government.  To strengthen its control, command economy, where government officials made all economic decisions, was put in place by the Communist Party.

Stalin forced peasants to give up ownership of their land and live on government-owned farms called collectives.  On a collective farm, all animals and equipment were owned by the state.  The government controlled the prices paid to the farmers for their products, and forced them to fill quotas, or production goals. 

Stalin also tried to spur industrial production, hoping to catch up to the United States as a world superpower.  People who refused to give up their factories and businesses and become workers of the government, or conform, were arrested and sent to prison.  Tens of millions of political protesters, uncooperative peasants and Stalin's personal enemies disappeared forever.

The People's Republic of China

As in Russia, the communist revolution in China was not one of workers vs. owners, but one of imperial government vs. poor starving peasants who felt that government had abandoned them.  After years of civil war, China became a Communist nation in 1949. The newly communist China looked to the Soviet Union for leadership, but quickly turned in a different direction.  

The leader of the Chinese Communist Party, Mao Zedong, wanted to transform China from an agricultural society into a modern industrial power.  Mao undertook a number of programs in order to achieve his goal.  He created communes, a Chinese version of the Russian collective, tried to renew Chinese culture. He also launched a series of agricultural and industrial production initiatives, and improved the social standing of women.

Conclusions
In both China and the Soviet Union, human rights were overlooked in the effort to create a strong Communist nation.  Tens of millions of dissenters, people who strongly disagree with a policy or idea, were killed. In each county, the goal of turning previously agricultural nations into powerful industrial giants only led to famine and further suffering for the general populace because of popular resistance to government policies.

Both China and the Soviet Union created something very different from the socialist utopia envisioned by Marx and Engels in 1848.   Mao and Stalin transformed their nations from absolute monarchies into totalitarian states with command economies. In both cases, private citizens ended up in even more strictly controlled societies, where personal freedoms were severely restricted, and most people feared to speak out against government corruption or abuse.

The Soviet Union fell apart in 1991 after most of its satellite states regained their independence.  China is still controlled by a communist government.