The Cournot Model is a foundational concept in oligopoly theory that describes how firms compete on the quantity of output they produce, rather than on price. In this model, firms make their production decisions simultaneously, aiming to maximize profits while considering the output levels of their competitors. This strategic interaction leads to a Nash equilibrium where no firm has an incentive to change its output level unilaterally, making it a key application of game theory in understanding firm behavior in markets with a few dominant players.