The Principles of Communism was written the year before the much more widely disseminated Manifesto of the Communist 
Party in conditions that would be hard to recognise today, lacking much of the terminology that Marxist theory now takes for granted. So why is it still of any usefulness or interest?
Engels answers 25 questions, starting with “What is communism?” and ending with a description of communists’ perspectives on other political parties.
After defining communism as simply, “the doctrine of the conditions of the liberation of the proletariat”, Engels explains what it means to be a proletarian and how the proletariat originated. He argues that this class is the child of the industrial revolution of the last half of the eighteenth century. The orthodoxy now is that this revolution was hugely beneficial for all involved. Engels instead says that the development of capitalist technology, with all its liberating potential, renders the workers’ means of production useless (the example of the loom is given). This gave rise to a much more unequal and polarised society, in which the class of “big capitalists” owns the vast majority of the means for subsistence and production, for example factories.
Das Krapital 