Oligopoly is a market with few sellers. Oligopoly is a market where a few dominant sellers sell differentiated or homogenous products under continuous consciousness of rival’s action.

The oligopoly market is concerned with group behaviour, and there are two types of oligopoly:
•Collusive oligopoly
•Non-collusive oligopoly

Non-collusive oligopoly includes three models:
•Cournot’s model
•Stacklberg’s model
•Kinked demand curve

Collusive oligopoly includes:
•Centralized cartels
•Market sharing cartels
•Price leadership

There are three types price leadership:
•Price leadership by low cost firm
•Price leadership by a large dominant firm
•Barometric Price leadership