Karl Marx was the primary author of the "Communist Manifesto," published in 1848. Co-written with Friedrich Engels, the manifesto outlined Marx's theories on class struggle, capitalism, and socialism. Marx argued that society is divided into classes—the bourgeoisie, who own the means of production, and the proletariat, who sell their labor. The manifesto called for the working class to rise against capitalist oppression and establish a classless society. It laid the foundation for Marxist theory, profoundly influencing socialist movements worldwide. The ideas presented in the "Communist Manifesto" continue to resonate in contemporary discussions about capitalism, class relations, and economic justice.