In a market where there is equilibrium, the resources are allocated in the best possible manner and there is 'allocative efficiency'.
Allocative efficiency is when situation where Marginal cost is equal to Marginal revenue.
However, this is not possible in the real world. Market failure exists when the resources are not allocated efficiently. Community surplus is not maximised and thus there is market failure. From a community's point of view, producer surplus is not equal to consumer surplus.
Market failure is thus caused by * Abuse of monopoly power * Lack of public goods * Under provision of merit goods * Overprovision of demerit goods * Environmental degradation * Inequality in distribution of wealth * Immobility of factors of production * Problems of information * Short termism
Externalities are a loss or gain in the welfare of one party resulting from an activity of another party, without there being any compensation for the losing party.
This activity can be due to consumption or production of a good or service.
If the third party suffers due to this activity then it is known as negative externality.
When the third party gains from this activity is it known as positive externality.
Marginal Private Benefit is the benefit which is derived by private individuals in the consumption of a good or service.
Marginal Private Cost is the cost of producing, specifically marginal costs, which are incurred by private individual while producing a good or service.
Marginal Social Cost is the total cost to society as a whole for producing one further unit, or taking one further action, in an economy. This total cost of producing one extra unit of something is not simply the direct cost borne by the producer, but also must include the costs to the external environment and other stakeholders.
The market demand and supply curves therefore reflect the MPB and MPC accruing to buyers and