Private Goods are products that can be purchased and consumed by an individual, and it is relatively easy to prevent others from using the same product. This is due to two defining characteristics of these goods: rivalry and excludability.

1. Rivalry means that when one person uses or consumes the good, it reduces the ability of others to use it. For instance, if someone buys and eats a loaf of bread, no one else can eat that same loaf.
2. Excludability refers to the idea that individuals can be easily prevented from using a product unless they pay for it. Goods like clothing or electronics are excludable because you cannot access or use them unless you purchase them.

Private goods, ranging from food to personal items, are common in everyday transactions. Examples include a cup of coffee or a smartphone, where the ownership and use by one person prevents others from enjoying the same product.

Common Resources

In contrast, common resources are goods that are available for everyone to use, but they can become depleted if overused. These are rival goods that are non-excludable, meaning:

1. Rivalry still applies because the consumption of the resource by one person reduces its availability for others.
2. Non-excludability means that it is difficult or impossible to prevent people from accessing and using the resource.

A classic example is fish in the ocean. Anyone can go fishing without having to pay for access. However, when too many fish are caught, the fish population could dwindle to unsustainable breeding numbers, reducing the availability of the fish for others. Forests, fresh water, and public grazing lands are other common resources that fall into this category.