Externalities
An externality is any valued impact (positive or negative) resulting from any ac- tion (whether related to production or consumption) that affects someone who did not fully consent to it through participation in voluntary exchange. Pricechanges in competitive markets are not relevant externalities because buyers and riety of externalities in our discussion of public goods-private supply of non and costs in the use of the divergence between ma rginal private and marginal social externalit congested resources We the label on non lem for those situations in which the good convey valued consumption of consenting parties is the by-product of either the production or some good access resources and ambient public goods, exter. As is the case with open because either the rights to ex- nality problems involve property rights rights are clusive the incompletely specified