What type of goods are defined as non-excludable and non-rival?

Public goods are categorized as non-excludable and non-rival, which means that they can be consumed by everyone without preventing others from doing the same. This characteristic means that individuals cannot be effectively excluded from using these goods, and one person's use does not reduce the availability for others. Examples of public goods include clean air, national defense, and public parks.

This classification is essential in economics because it explains why public goods are often provided by the government or through collective effort, as the private market might underprovide these goods due to the inability to charge individuals for their use. Understanding public goods also helps in analyzing issues such as free riding, where individuals benefit from the good without contributing to its provision.