The proletarian are the ones who work and work and work and never get ahead because they don't own what they create. They're working for wages. In Karl Marx's mind, everything is tainted by this, relationships and money and opportunity, everything. On the other side, you have the bourgeoisie. Now, if that's just not the most fun word to say ever, bourgeoisie. The bourgeoisie are the property owners, the artisans and the merchants, the business owners, the ones that really are making more money in Marx's mind with working less. This ownership alone is giving them the right to capital and this is splitting the world.