The tragedy of the commons is an economic issue where individuals, acting in their self-interest, over-consume shared resources, leading to depletion and harm to all. This problem arises when common resources are non-excludable and rival, resulting in negative externalities, and typically requires government intervention to prevent destruction. Examples include freeway traffic, environmental pollution, and fish stocks in the ocean, highlighting the need for solutions like regulation or taxation to mitigate overconsumption.