Private good

A good whose consumption by one person reduces what remains for others and from which nonpayers can be excluded.

Rivalry (economics): A property of a good whose consumption by one person reduces the amount available to others. Rivalry is the scarcity condition that separates private goods from nonrival goods.
Market: An arrangement through which buyers and sellers exchange goods, services, or assets. Markets coordinate the purchase and sale of many private goods.
Public good: A good that is nonrival in consumption and from which people cannot readily be excluded. It differs from a private good on both rivalry and excludability.
Welfare economics: The study of how economic arrangements affect social well-being and the distribution of resources. It evaluates whether private-good markets allocate resources efficiently and fairly.
Excludability: The ability to prevent people from using a good unless they meet specified conditions, often payment. Exclusion lets sellers reserve a private good for paying consumers.
Price mechanism: The use of prices to communicate scarcity and coordinate economic decisions. Prices can ration rival goods among consumers willing and able to pay.
Common-pool resource: A resource from which exclusion is difficult but whose use by one person reduces availability to others. It is rival like a private good but difficult to restrict to paying users.
Consumer surplus: The difference between what a buyer is willing to pay and the price actually paid. Purchases of private goods generate measurable gains to buyers beyond their expenditure.
Economic good: A scarce item or service that can satisfy human wants and has an opportunity cost. Private goods are one class of scarce goods in economic analysis.
Consumer choice: The decisions individuals make about which goods and services to purchase under constraints. Private goods let consumers select units for their own use.

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