A vertical supply curve indicates that the same fixed quantity will be supplied no matter the price. In economics, the supply curve represents the relationship between the quantity of a good that producers are willing to supply and the price of that good. A vertical supply curve means that at every possible price, the quantity of the good supplied will be the same.
This situation typically arises when the production of the good is fixed and cannot be increased or decreased in response to changes in price. For example, a rare vintage wine that is no longer being produced may have a vertical supply curve, since there is a fixed quantity of that wine available, and no amount of price change can increase the supply. Another example could be a limited edition collector's item, where the number produced is fixed and cannot be increased in response to changes in demand or price.
It's worth noting that a vertical supply curve is rare in most markets, as producers are usually able to adjust their output in response to changes in price. In most cases, the supply curve is upward sloping, indicating that as the price of a good increases, producers are willing to supply more of it.