Final answer:
A monopoly refers to a market structure where a single firm controls the market for a product with no close substitutes, allowing them to set prices without competitive pressure. This can happen in industries where barriers to entry are high or where one firm has a significant market share, as seen with Microsoft in the operating systems market.
Step-by-step explanation:
A monopoly is an entity, such as a firm, with a monopoly that gives it the power to influence the price it charges as the good it produces does not have perfect substitutes. In a monopolistic market, one firm produces all of the output in a market. Since the firm faces no significant competition, it can charge any price it wishes, as it is constrained only by the market demand curve. A monopoly, by definition, refers to a single firm; however, in practice, the term is commonly used to describe a market in which one firm has a very high market share. An example of a company that has been regarded as a monopoly is Microsoft, due to its dominance in the operating systems market.