Editing Marginal cost (section)

== Perfectly competitive supply curve ==
The portion of the marginal cost curve above its intersection with the average variable cost curve is the supply curve for a firm operating in a [[perfect competition|perfectly competitive market]] (the portion of the MC curve below its intersection with the AVC curve is not part of the supply curve because a firm would not operate at a price below the shutdown point). This is not true for firms operating in other market structures. For example, while a monopoly has an MC curve, it does not have a supply curve. In a perfectly competitive market, a supply curve shows the quantity a seller is willing and able to supply at each price – for each price, there is a unique quantity that would be supplied.