the uncompensated impact of one person's actions on the well-being of a bystander
internalizing an externality
altering incentives so that people take account of the external effects of their actions
Coase theorem
the proposition that, if private parties can bargain without cost over the allocation of resources, they can solve the problem of externalities on their own
transaction costs
the costs that parties incur in the process of agreeing and following through on a bargain
Pigovian tax
a tax enacted to correct the effects of a negative externality