Karl Marx used the word "proletariat" to describe people who did not own the means of productions (such as factories and land) and had to work for others for a wage. He thought the proletariat class could overthrow the capitalist system and society more just. He learned about the word while studying Roman law in Berlin. In Marxist theory, the lumpenproletariat ("rag-proletariat" in German) were a class of people who were not interested in revolution.