Final answer:
A monopoly is when a single firm has total control of a market for a certain product, allowing it to charge any price it wishes.
Step-by-step explanation:
A monopoly is when a single firm has total control of a market for a certain product. This means that there is no competition in the market, allowing the firm to charge any price it wishes. While a monopoly refers to a single firm, in practice, it can also be used to describe a market where one firm has a very high market share. The U.S. Department of Justice often uses this definition. For example, Microsoft has been considered a monopoly because of its domination of the operating systems market.