Mariginal soscial benefit and Marginal social cost

Marginal social benefit
The marginal social benefit curve is the market demand curve of the good, i.e. the sum of all consumer’s marginal benefits.

Marginal social cost
The marginal social cost curve is is the supply curve of the good,i.e. the sum of all producter’s marginal costs to supply a good.

A competitive market will use resources efficiently. Goods are produced up to the point where the marginal benefit is equal to the marginal cost, and the sum of consumer surplus and producer surplus is maximized.