Communism is a socioeconomic system in which there are no classes (social classes), and everything is of common ownership (including production (produce)). There is no "private" property, no hunger, no poverty, and no discrimination, we are all human, we are all one people united. The economic balance is achieved through collectivization, in which all resources are sent to the head government, then equally distributed among all citizens regardless of their positions. When this is done; the citizens are to continually give to their fullest abilities, while they will receive according to their needs (or more). Once this is completed (and if conditions in the world are favorable) the government will be decentralized into regional governments. All the while keeping in line with this ideal. The end result of this whole process is utopia. It is a system of peace and love.
That is "Pure" Communism.
However many are taught only of totalitarian (dictatorship) philosophies that "fit" with Communism. These include Pol Pot(ism), Maoism, and Bolshevism. In all reality these systems are more Fascist than anywhere near Communistic. All these forms do is bring all the power and money to small group of individuals. However those are the forms that are typically thought of when people say "Communism", but they are as relevant to the ideas of Communism as the spanish inquisition was to Christianity, or as Hitler was to Socialism.
Now onto other, aspects of Communism...
The way it is to be brought about is typically through revolution, though it is not limited to it. The Communistic Revolution occurs when the proletariat (the working and oppressed) have reached the breaking point, they will revolt against the bourgeoisie and oust the capitalist system that is in place. From there is the division point of many different forms of "Communism". In Leninism/Bolshevism, for instance, there is to be a one party government led by a single person (Totalitarian). In Soviet (the original ideology) / Christian Communism, there is to be a multi-leftist-party council in government which take votes to make decisions (Democracy). There are other forms that are around (such as Communistic anarchy) however the two forms of government mentioned are the most predominant.
Besides how government is run, there are several more aspects that can effect the lives of civilians, such as freedom of speech, and religion. Freedom of speech is a aspect that never been thought of to fit-in with Communism, though is actually needed to see both sides of an argument, which is essential in a Democratic government. This is not the case in a totalitarian government, which is why people think that Communism is "anti-freedom", since the many forms practiced used that kind of system. Religion is another aspect people have deluded views over; Communism cannot be defined as either pro or anti religion, only it's varying forms can. Bolshevism for instance is strongly anti-religion, which is why the U.S.S.R was an atheist state, as they had concluded religion was a tool by the bourgeoisie to corrupt people. The Christian Communists however strongly support religion (especially Christianity), as they see it as a way to give people hope and inspire them.
Communism in it's purest form (regardless of type) requires a few things to work properly. Firstly, the people of the nation need to be motivated, caring, selfless, and hardworking, hard-to-find qualities... Secondly, the leader/s of the nation need to have will power, be incorruptible, as they/he will (more or less literally) have the entire nation in their/his hands. Thirdly, the whole plan has to be carried out efficiently, with very little to no mistakes. These, along with other tedious details, are the reasons why Communism is perfect but is nearly impossible to successfully achieve.
Thank you for reading my summary of the subject of Communism, if you wish to learn more please seek additional sources. Beware of biased writings, try to find unbiased sources for trustworthy information.
I don't mind a good political argument but please keep all comments reasonable, no "Communism is stupid, etc."