Pollution is the most obvious example of externalities leading to "market failure". Clean air, similarly, is the most basic example of a public good subject to

Pollution is the most obvious example of externalities leading to "market failure". Clean air, similarly, is the most basic example of a public good subject to the free rider problem. https://en.wikipedia.org/wiki/Free-rider_problem https://en.wikipedia.org/wiki/Free-rider_problem