this is the definition wikipedia gave for communism because im too lazy to do it myself:Communism is a socioeconomic structure that promotes the establishment of a classless, stateless society based on common ownership of the means of production.[1] It is usually considered a branch of the broader socialist movement that draws on the various political and intellectual movements that trace their origins back to the work of theorists of the Industrial Revolution and the French Revolution[2]. Communism attempts to offer an alternative to the problems believed to be inherent with capitalist economies and the legacy of imperialism and nationalism. Communism states that the only way to solve these problems would be for the working class, or proletariat, to replace the wealthy bourgeoisie, which is currently the ruling class, in order to establish a peaceful, free society, without classes, or government.[3] The dominant forms of communism, such as Leninism, Trotskyism and Luxemburgism, are based on Marxism, but non-Marxist versions of communism (such as Christian communism and anarchist communism) also exist and are growing in importance since the fall of the Soviet Union.

and here is a link to it there is a load more info here it also explains other types of communism such as anarcho-communism, it is the first sit i found so far that does that so ........yeah
http://en.wikipedia.org/wiki/Communism

oh and here is another definition i just found that i think explains some other points:

Communism is a political ideology that seeks to establish a future, without social class, or formalized state structure, with social organization based upon common ownership of the means of production. It can be classified as a branch of the broader socialist movement. Communism also refers to a variety of political movements which claim the establishment of such a social organization as their ultimate goal.

Early forms of human social organization have been described as "primitive communism." However, communism as a political goal generally is a conjectured form of future social organization which has never been implemented. There is a considerable variety of views among self-identified communists, including Maoism, Trotskyism, council communism, Luxemburgism, and various currents of left communism, which are generally the more widespread varieties. However, various offshoots of the Soviet and Maoist forms of Marxism-Leninism comprise a particular branch of communism that has been the primary driving force for communism in world politics during most of the 20th Century.

all i know is that communism in high school history classes,
sounds like its a pandemic of some kind of brainwashing,
but who believes what the australian government wants us to learn is the truth?
veering offtopic sorry..

it is an interesting topic though, so start a new thread for it!