In a monopoly, how many sellers control the market?

In a monopoly, there is only one seller controlling the entire market. This singular presence means that the monopolist has significant market power, allowing it to set prices and dictate supply levels without competition from other firms. The lack of alternative sources of the product or service grants this seller the ability to influence the market dynamics, often leading to higher prices and potentially less innovation than in more competitive markets.

This characteristic is fundamental to understanding monopolistic markets, distinguishing them from other market structures like oligopoly or perfect competition, where multiple sellers exist.