In congestion or overuse, because they are subtractable. the common-pool resource typically consists of a core resource e.g. water or fish, which defines the stock variable, while providing a limited quantity of extractable fringe units, which defines the flow variable. While the core resource is to be protected or nurtured in structure to permit for its non-stop exploitation, the fringe units can be harvested or consumed.
Common-pool resources may be owned by national, regional or local governments as public goods, by communal groups as common property resources, or by private individuals or corporations as private goods. When they are owned by no one, they are used as open access resources. Having observed a number of common pool resources throughout the world, Elinor Ostrom noticed that a number of them are governed by common property protocols — arrangements different from private property or state supervision — based on self-management by a local community. Her observations contradict claims that common-pool resources must be privatized or else face damage in the long run due to collective action problems leading to the overuse of the core resource see also Tragedy of the commons.