According to garret hardin what is "the tragedy of the commons"

The tragedy of the commons is an economic theory of a situation within a shared-resource system where individual users acting independently according to their own self-interest behave contrary to the common good of all users by depleting or spoiling that resource through their collective action. The concept and name originate in an essay written in 1833 by the Victorian economist William Forster Lloyd, who used a hypothetical example of the effects of unregulated grazing on common land (then colloquially called "the commons") in the British Isles.[1] The concept became widely known over a century later due to an article written by the ecologist Garrett Hardin in 1968.[2] In this context, commons is taken to mean any shared and unregulated resource such as atmosphere, oceans, rivers, fish stocks, or even an office refrigerator.

It has been argued that the very term 'tragedy of the commons' is a misnomer per se, since 'the commons' originally referred to a resource owned by a community, and no individual outside the community had any access to the resource. However, the term is presently used when describing a problem where all individuals have equal and open access to a resource. Hence, 'tragedy of open access regimes' or simply 'the open access problem' are more apt terms.[3]:171

The tragedy of the commons is often cited in connection with sustainable development, meshing economic growth and environmental protection, as well as in the debate over global warming. It has also been used in analyzing behavior in the fields of economics, evolutionary psychology, anthropology, game theory, politics, taxation and sociology.

Although commons have been known to collapse due to overuse (such as in over-fishing), abundant examples exist where communities cooperate or regulate to exploit common resources prudently without collapse.