What characteristic describes perfectly inelastic supply?

Perfectly inelastic supply is characterized by the fact that the quantity supplied remains constant regardless of any changes in price. This situation is depicted graphically as a vertical supply curve. Since suppliers cannot increase the quantity provided to the market no matter how high the price goes—because the good or service is fixed in quantity, or due to other constraints—their supply is completely unresponsive to price changes.

This means that, even if demand increases and prices rise, the quantity supplied will not change. A classic example would be life-saving drugs or a piece of art from a famous artist; no matter how much someone is willing to pay, the quantity available does not change in response to market prices. Understanding this concept is crucial as it highlights the limitations of supply in specific contexts, illustrating scenarios where market forces may not function in typical ways.