This document defines monopoly and provides examples. It discusses that a monopoly is a single seller of a unique product without duplication. Examples given include Shimano and Debeers diamonds. Characteristics of a monopoly include single seller, unique product, barriers to entry, and being a price maker. Barriers to entry that can create a monopoly include economies of scale, patents, copyrights, licenses, franchises, and network externalities. Monopolies can be natural, geographic, technological, or government created.