The beginning of Scientific Socialism: Proletarian oppression
"The history of all hitherto existing society is the history of class struggles. Freeman and slave, patrician and plebeian, lord and serf, guild master and journeyman, in a word, oppressor and oppressed..."(Karl Marx, Communist Manifesto)
Since the beginning of history, there have been class divisions in society and from that, struggles by the lower classes to improve their positions. The bourgeoisie and proletariat of the industrial revolution are no different. The bourgeoisie were concerned only with profit through the market with factories or with property. The working proletariat concerned with making enough to live and eat.
La sortie du bourgeois, Jean Béraud, 1889
While the bourgeoisie often lived in comfort from their commercial ventures, the proletariat endured dangerous working conditions with long hours and low wages.
Scientific (Marxist) Socialism:
"The immediate aim of the Communists is the same as that of all the other proletarian parties: formation of the proletariat into a class, overthrow of the bourgeois supremacy, conquest of political power by the proletariat." The communist manifesto
The communist ideology addresses property relations between the bourgeoisie and the proletariat. It wants the equality between the bourgeoisie social class and the proletariat.
Its view on the current class is that the bourgeoisie are extorting the proletariat for their own commercial interest.
They hope to establish this equality by abolishing private property of the Bourgeoisie.
It is unique because they represent the working class movement as a whole and work for the " common interest of the entire proletariat, independently of their nationality."
Karl Marx and Friedrich Engels wrote the communist manifesto that outlines this ideology in 1848. It attracted intellectuals and members of the working class as well all across western Europe.