What exactly is communism?

Ive heard a lot about it, many people seem to hate it and for that same reason I wish to learn about it so i don't blindly denounce it (or accept it) into or from my life. Please I want unbiased answers nothing like "commi bast*rd" comments or "communism rules" I wish to learn about it not hear short sentences on your opinion of it. Thank you to any who try to teach me about it.