Monopoly and oligopoly are two economic conditions of the market. Both are likely to coexist in our world and differ from each other. In this written article I will describe the two market conditions. I will describe the characteristics of each in terms of the number of suppliers, product differentiation, advantages and disadvantages, and the most challenging types of barriers to entry that exist in both market structures. A monopoly is a market structure in which there is only one producer/seller for a product or service. In other words, the individual business is the industry. That single manufacturer/seller has the power to influence pricing and market decisions. In an extreme case, a monopolist might be the sole owner and seller of a product or service in an industry. A monopoly has a huge amount of buyers and never has large competitors. This is because it has the power to destroy competition. A monopoly controls the prices of goods and is also the creator of prices. Unlike a perfect competitive market, in a monopolistic market consumers/customers do not have perfect information about the products or services they purchase. Consumers have limited choices and must choose between what is provided to them. The monopolist claims all the power while consumers have no choice. For example: Imagine if Comcast was the only media company that could provide cable TV. If someone wanted to watch TV, they would have to purchase Comcast's cable service at any price, as they would be the only cable TV provider. There are advantages and disadvantages of a monopoly. One of the advantages is large profits. A monopoly enjoys economies of scale, since it is the sole supplier of a product... average paper... that is not competitive with other firms. If companies reduced prices, they would gain a significant increase in market share, however companies are unlikely to allow this. If this happens, other companies will also follow and reduce prices as a result. Demand will increase only by a small amount: demand is inelastic for a reduction in prices. Simply put, monopoly and oligopoly are two market structures that might have their differences but definitely share similarities. In both market structures, there are dominant firms that have control over the markets in which they operate. Both facilities need high barriers to entry for them to exist. Monopolistic and oligopolistic firms are very large and both produce large profits. Advantages and disadvantages coexist in both market structures, but this is ultimately why they differ from each other.