This document discusses oligopoly, which is a market structure with a small number of firms that interact strategically. It describes the key characteristics of oligopoly including few sellers, product homogeneity, and interdependence between firms. The document then explains several models of oligopoly analysis including the Cournot, Stackelberg, and Bertrand models. As an example, it works through a Cournot model problem to find the equilibrium output level for two firms.