This chapter introduces the concept of commons and includes a discussion of terminology. Elinor Ostrom cited the example of forest commons in Uganda, which had been investigated by political scientist Nathan Vogt. She concerns environmental sustainability, and problems such as climate change, brought her to focus increasingly on the concept of social-ecological systems. Before 1968 publication of Garrett Hardins Tragedy of the Commons paper in the journal Science, it was generally assumed by academics that collective management of a resource would lead to chaos. Margaret Levi argues that self-organised systems often rely on semi-voluntary cooperation rather than complete cooperation or coercion. The Norwegian Raw Fish Act of 1938 allowed fishermen to negotiate and set an enforceable landing price for their fish. Harold Demsetz recognised that collective property ownership was possible and argued that for many nomadic peoples, where population density was low, common property was an attractive option.