Industrial organization is the field of economics which studies the behaviors of the firms when they face situations of imperfect competition.
Industrial organization does not assume the assumptions of perfect competition. It considered markets in which there are a limited number of firms which have a monopoly power. Those firms can invest to protect themselves from competition, benefit from information asymmetries, and the goods they produce are similar, but not identical.
One of the most common kind of imperfect competition is the duopoly, a situation in which only two firms control the market. In such a situation, producers have not the same strategies as when they face a larger competition. The strategy chosen in order get the higher profit possible will depend on the kind of interaction the two producers have. There are several possibilities :