A pure monopoly is a market structure where one company is the single source for a product and there are no close substitutes for the product available. Pure monopolies are relatively rare. In order for a provider to maintain a pure monopoly, there must be barriers preventing competitors from entering the market. Let's look briefly at some possible barriers. A market in which one company has control over the entire market for a product, usually because of a barrier to entry such as a technology only available to that company.