The theoretical concept of public goods does not distinguish geographic region in regards to how a good may be produced or consumed. However, some theorists, such as Inge Kaul, use the term "global public good" for a public good which is non-rivalrous and non-excludable throughout the whole world, as opposed to a public good which exists in just one national area. Knowledge has been argued as an example of a global public good, but also as a commons, the knowledge commons.