How does price ceilings affect supply and demand?

A price ceiling prevents a price from rising above the ceiling. It represents an upper limit on the price of something. If wheat has a price ceiling of $400 per metric tonne, $400 is the highest amount any what supplier can charge. If the market price for wheat is below the ceiling, say $200 in this example, then the ceiling has no effect on prices; the ceiling is not binding. If the market price is higher than the ceiling, supply and demand cannot reach equilibrium and there is a shortage in the commodity. Artificially low prices result in demand that exceeds supply. The price, however, remains stuck at the ceiling.