1) What is Communism?
Communism is the doctrine of the conditions of the liberation of the proletariat.

2) What is the proletariat?
The proletariat is that class in society which lives entirely from the sale of its labour and does not draw profit from any kind of capital; whose weal and woe, whose life and death, whose sole existence depends on the demand for labour – hence, on the changing state of business, on the vagaries of unbridled competition. The proletariat, or the class of proletarians, is, in a word, the working class of the 19th century.