Final answer:
A pure monopoly is a market where one firm has total market power and is the only producer, allowing it to set prices without competition.
Step-by-step explanation:
A monopoly is a market structure that consists of only one seller or producer. A monopoly limits available substitutes for its product and creates barriers for competitors to enter the marketplace. Monopolies can lead to unfair consumer practices. A pure monopoly has the overall market to itself, because it is the only seller in a market. Unlike perfect competition where firms do not possess market power and adhere to market prices, a monopoly has significant market power. In a monopolistic market structure, a single firm is responsible for producing all the market's output, allowing it to set prices freely, limited only by the market's demand curve.
While a pure monopoly technically involves a single firm, the term can also apply to a firm holding a predominant market share, which is also how the U.S. Department of Justice interprets it. An example of this would be Microsoft, which has been considered a monopoly in the operating systems market due to the lack of close substitutes to its products.