How does a quasi public good differ from a pure public good?

A quasi-public good, also known as a semi-public good, is a type of good or service that exhibits some but not all of the characteristics of a pure public good. While both quasi-public goods and pure public goods are non-excludable in nature, meaning that once provided they cannot be easily denied to anyone who wants to use them, there are some key differences between the two:

1. Rivalry: Pure public goods are non-rivalrous in consumption, meaning that one person's use of the good does not diminish its availability to others. Quasi-public goods, on the other hand, may be rivalrous to some extent, meaning that the consumption of one person may limit the availability or quality of the good to others. For example, a park may be open to everyone, but if it becomes too crowded, the experience for each person may be diminished.
2. Excludability: While both pure public goods and quasi-public goods are non-excludable, meaning that people cannot be easily excluded from using them, quasi-public goods may be partially excludable. For example, while anyone can use a public park, some parts of the park, such as a sports facility, may require a fee or membership to use.
3. Financing: Pure public goods are typically financed through government funding, while quasi-public goods may be funded through a combination of government funding, user fees, and other sources of revenue.

Examples of quasi-public goods include public transportation, roads, parks, and libraries, which are accessible to everyone but may be rivalrous in consumption and partially excludable.