In the context of demand, what does it mean for a good to have a vertical demand curve?

When a good has a vertical demand curve, this indicates that consumers are completely insensitive to price changes for that good. This phenomenon happens typically in situations where the good is a necessity and there are no close substitutes available. As such, no matter how much the price increases or decreases, the quantity demanded remains constant.

This occurs because consumers are willing to buy the same amount of the good regardless of price fluctuations, reflecting an absolute necessity in their purchases. Goods that often exhibit vertical demand curves include life-saving medications or basic necessities like water in an emergency situation.

An understanding of this concept is crucial, as it differentiates between varying degrees of elasticity in demand; a vertical demand curve represents an extreme case of inelastic demand where price does not influence consumer behavior at all.