A market structure where there is only one seller of a particular product is?

A market structure where there is only one seller of a particular product is known as a monopoly. In a monopoly, the single seller controls the entire supply of the product and can influence prices, often leading to less competition and higher prices for consumers. This market structure typically arises due to high barriers to entry for other potential competitors. Monopolies can result in decreased innovation and efficiency compared to more competitive markets.