Final answer:
A monopoly is when a person or group has exclusive control over a product or service within a given region. This can happen when a single firm sells a product for which there are no close substitutes.
Step-by-step explanation:
In the context of economics, when a person or group has exclusive control over a product or service within a given region, it is called a monopoly. A monopoly arises when a single firm sells a product for which there are no close substitutes. An example of a monopoly is Microsoft's domination of the operating systems market.