Common resources are natural resources that are available to everyone and are not owned by any single individual. Examples include air, water, forests, and fisheries. These resources are essential for human survival and well-being, but they can be overused or depleted if not managed properly. The challenge with common resources is that they are susceptible to the "tragedy of the commons," a situation where individuals act in their own self-interest, leading to the degradation of the resource. Sustainable management practices are necessary to ensure that these resources remain available for future generations while balancing the needs of current users.