1.6.1—Free and private goods

A free good is available in enough quantity that no opportunity cost is normally required to use it. A private (economic) good is scarce, has an opportunity cost and can usually be made excludable through ownership or price.

The classification depends on context and technology. Air may be free in one setting but scarce and priced when cleaned or supplied in a cylinder.

A loaf of bread is a private good: using it leaves less for someone else and a seller can restrict access. Sunlight in an open field is usually treated as a free good.

“Free” means no opportunity cost, not merely zero money price; a free-to-user service may still use scarce resources.