Which of these describes a characteristic of public goods?

Public goods are defined by two main characteristics: they are non-excludable and non-rivalrous.

Non-excludable means that once a public good is provided, it is not possible to prevent individuals from using it. This characteristic is evident in services such as national defense or public parks, where once these goods are provided, everyone can benefit from them without being excluded.

Non-rivalrous indicates that one person's use of the good does not diminish the availability of the good for another person. For instance, when one person enjoys a public good like street lighting or clean air, it doesn't reduce the amount available for others; everyone can benefit from these goods simultaneously without interference.

Therefore, the combination of these two characteristics – being both non-excludable and non-rivalrous – is essential in defining public goods. This concept is crucial for understanding how certain services and resources are managed within the economy, particularly when considering funding and provision of these goods through collective means rather than individual consumption.