Tragedy of the Commons:The situation that can occur when individuals, acting independently and rationally according to their own self-interest, will ultimately deplete or destroy a shared resource, even when it is not in anyone's long-term interest for this to happen.
Public Goods:Goods or services that are non-rivalrous (one person's consumption does not reduce another's) and non-excludable (it is difficult to prevent people from accessing them), such as national defense or public parks.
Common-Pool Resources: Resources that are rivalrous (one person's consumption reduces another's) but non-excludable, such as fisheries, forests, and groundwater.