The bourgeoisie is the ruling class in capitalist society; it owns the means of production and has a decisive influence on its production, while living at the expense of the exploitation of wage labor.
Throughout history, the term "bourgeoisie" has had different meanings, reflecting different historical conditions. While in the Middle Ages, the bourgeoisie was a revolutionary social class during the transition stage between feudalism and capitalism, in today's age, the bourgeoisie is a reactionary class, fighting against the development of productive forces when there is not surplus-value to be extracted from workers. In contrast, the proletariat is the revolutionary class which will liberate the productive forces and develop the socialist mode of production.