What is the difference between Consumer Surplus and Producer Surplus?

In welfare economics, market efficiency is evaluated by the sum of consumer and producer surplus.

• Consumer Surplus (CS): The difference between the maximum price a consumer is willing to pay and the market price actually paid. Visually, it is the area below the demand curve and above the market price line.
• Producer Surplus (PS): The difference between the actual market price received by a producer and the minimum price at which they are willing to supply the good (marginal cost). Visually, it is the area above the supply curve and below the market price line.

Deadweight Loss (DWL): Any policy (such as a tax, quota, or price ceiling) that reduces the combined consumer and producer surplus creates a deadweight loss to society.