Welfare effects of price ceilings. Price ceiling reduces the equilibrium quantity. The lower quantity results in lower consumer surplus lower producer surplus Price ceilings result in a net loss in welfare. Given shortage, firms can choose how they will discriminate. Regular customers often benefit.
Price floors are legislatively imposed minimum prices.
Set above equilibrium price to be effective. Artificially high price leads to a persistent surplus. High price decreases quantity demanded. High price increases quantity supplied. Persistent surplus requires some mechanism to remove the excess supplies from the market.