Composing the class of modern Capitalists, the bourgeoisie are the employers of wage laborers, and the owners of the means of production. The Manifesto shows how the modern bourgeoisie is the product of several revolutions in the mode of production and of exchange. The development of the bourgeoisie began in the earliest towns, and gained momentum with the Age of Exploration. Feudal associations couldn't provide for increasing markets, and the manufacturing middle class took its place. However, markets kept growing and demand kept increasing, and manufacture couldn't keep up. Manufacture was replaced by "Modern Industry," and the industrial middle class was replaced by "industrial millionaires," the modern bourgeois. The bourgeoisie have become powerful, and pushed the traditional three estates from the Ancien Regime into the background. The development of the bourgeoisie as a class was accompanied by a series of political developments. With the development of Modern Industry and the world-market, the bourgeoisie has gained exclusive political sway. The State serves solely the bourgeoisie's interests. .
Proletariat.
The proletariat is defined as the class of modern wage-laborers. They do not have their own means of production, and therefore they are forced to sell their own labor in order to survive. The proletarians can only live as long as they can find work, and they can find work only as long as their labor increases capital. They are a commodity, and are vulnerable to the fluctuations of the market. Due to the development of machines and the division of labor, the proletarian's work has simply become an appendage of a machine. As his work becomes more repulsive, his wage only decreases. Furthermore, no sooner does the worker get his wages from his exploitative boss, then he is exploited by other bourgeoisie, such as his landlord. The Manifesto describes the proletariat as the only true revolutionary.