The tragedy of the commons is a problem that occurs when individuals exploit a shared resource to the extent that demand overwhelms supply and the resource becomes unavailable to some or all.
Garret Hardin, an evolutionary biologist, wrote "The Tragedy of the Commons," which was published in the journal Science in 1968. Hardin's main concern was overpopulation. He used the example of commonly-used grazing land. According to Hardin, the land could provide adequately as long as the number of herders grazing cattle on it was kept in check, through natural population control mechanisms such as war and disease.
If the numbers were to increase as a result of those checks being overcome, the land would be no longer sufficient to support the population. Each person sharing the land, acting in self-interest, would continue to tax the resources of the commons, despite the fact that if enough people do so, the land will be damaged and unable to support them.
The tragedy of the commons has implications for the use of resources and sustainability. Depletion of non-renewable resources is an example of the tragedy of the commons in action. Non-renewable resources, such as water, are often used as if the supply were limitless. Similarly, the reliance on fossil fuels is not only unsustainable but is demonstrably damaging the environment.
The Internet is sometimes referred to as a commons, a shared resource subject to the same pressures of self-interest and exploitation that lead to damage in the physical environment. In either context, the solution to the problem involves management and regulation of resources with the goal of maintaining sustainability.