The article explains how goods and services can be divided based on their characteristics of exclusion and consumption. Some items can keep people from using them if they don't meet certain conditions, and some can be used by many without running out. This sorting leads to four main kinds of goods: individual, toll, common-pool, and collective goods. Each type has a role for either the government or private groups in supplying them. By understanding these different types of goods and how they are used, society can figure out who should provide them.