Public goods are concepts corresponding to private goods, and consumption is non-competitive and non-exclusive. Generally, it cannot or cannot be effectively provided by enterprises and individuals through market mechanisms, mainly by the government.

Quasi-public goods are public goods with great externalities in consumption. It has two characteristics: ① competition in consumption, that is, one person's consumption of an item may reduce the consumption (quality and quantity) of others; ② Consumption is exclusive, that is, only those who pay by price can enjoy the item. There are a lot of quasi-public goods in reality, such as public facilities, public education and medical services in most cities.