Goods: All things from which individuals derive satisfaction or happiness
Services: Mental or physical labor or help purchased by consumers. Examples are the assistance of physicians, lawyers, dentists, repair personnel, house cleaners, educators, retailers, and wholesalers; items purchased or used by consumers that do not have physical characteristics.
Private goods and services: Goods that can be consumed by only one individual at a time. Private goods and services are subject to the principle of rival consumption
Public goods and services: Goods for which the principle of rival consumption does not apply; they can be jointly consumed by many individuals simultaneously at no additional cost and with no reduction in quality or quantity.
Principle of rival consumption: The recognition that individuals are rivals in consuming private goods because one person's consumption reduces the amount available for others to consume.