What is conflict theory?

The best known of all sociological theories, at least in American sociology, is conflict theory. It has roots in Marx's theory, and much of it can be seen as an inversion of structural-functionalism. Yet, while structural-functionalism emphasizes what is positive about society, conflict theory focuses on what's negative. To the structual-functionalists, society is held together by consensus: virtually everyone accepts the social structure, its legitimacy, and its benefits. However, to the conflict theorists, society is held together by coercion: those who are adversely affected by society, especially economically, would rebel if it wasn't for coercive forces like the police, the courts and the military.