The answer is a public good.
A private good is both rival and exclusive. This means that one person's consumption of the good reduces the amount available for others, and people can be excluded from using it if they do not pay for it. Examples include food, clothing, and cars.
A public good is neither rival nor exclusive. This means that one person's consumption of the good does not reduce the amount available for others, and it is difficult or impossible to exclude anyone from using it. Examples include national defense, public parks, and clean air.
A quasi-private good, also known as a club good, is non-rival but exclusive. This means that one person's consumption does not reduce the amount available for others, but people can be excluded from using it if they do not pay for it. Examples include subscription-based services like cable TV or private clubs.
An external good is not a standard term in economics. However, externalities refer to the positive or negative effects of a good or service on third parties who are not directly involved in the transaction. This is not the same as the classification of goods based on rivalry and exclusivity.
An open access good is rival but non-exclusive. This means that one person's consumption of the good reduces the amount available for others, but it is difficult or impossible to exclude anyone from using it. Examples include fisheries and common grazing lands.
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