The tragedy of the commons is the idea that when a resource is shared, each person gains by using a little more of it, but the cost falls on everyone, so the resource collapses even though nobody wanted that outcome. Each herder who adds one more animal to a common pasture keeps the whole profit of that animal while sharing the damage to the grass. Ecologist Garrett Hardin popularised the phrase in a 1968 essay, though versions of the idea go back to Aristotle. Later research found that communities often avoid this trap through agreed rules, and Elinor Ostrom, who won the Nobel Prize in Economics, showed that local groups manage shared fisheries and forests successfully when they set their own limits and enforce them. Hardin's own policy conclusions, about population control and migration, were heavily criticised, so the idea is usually taught now as a problem to design around rather than a law of nature.

Hampi is a UNESCO World Heritage Site in Karnataka, India, with more than 1,600 surviving remains spread over 4,100 hectares. It was the capital of the Vijayanagara Empire from 1336 to 1565. Travellers from Persia and Portugal described it as a prosperous, wealthy and grand city with temples, markets and farms along the Tungabhadra River. By 1500 it was estimated to be the world's second-largest city after Beijing, and probably India's richest at the time. In 1565 a coalition of Muslim sultanates defeated the Vijayanagara Empire, its capital was conquered and destroyed, and the city was left in ruins. Hampi remains a religious centre, with the active Virupaksha Temple at its heart.