Economic surplus

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.

 References 

Category:Microeconomics
Category:Welfare economics