A common good is a resource which is non-excludable (Excludability) and rivalrous (Rivalry—like irrigation systems (which can be polluted or over-extracted), fish stocks, and mined metals. These types of goods can suffer from overexploitation due to collective action problems: for instance, each fisherman might prefer to collect as many fish as he can, but if everyone does this, the fishery will collapse.
Elinor Ostrom called these “common-pool resources,” and in Governing the Commons she suggests a framework for their collective management under common property protocols which introduce some properties of excludability (particularly to individuals outside the community) and which align the resource’s ongoing provision with its appropriation.
Ostrom, E. (2015). Governing the Commons: The Evolution of Institutions for Collective Action. Cambridge University Press. https://doi.org/10.1017/CBO9781316423936