Economic surplus
monetary benefit that accrues to parties to an economic transaction / From Wikipedia, the free encyclopedia
An economic surplus is when you have more of something in the economy than people demand. There are two types:
Consumers' surplus is the gain by consumers who can buy a product for less than the highest price that they would be willing to pay.
Producers' surplus is the amount got by producers who sell at a market price higher than the least they would be willing to sell for.[1][2]