Free-Rider Problem: The tendency for individuals to benefit from public goods or collective efforts without contributing to the costs or efforts required to produce them.
Tragedy of the Commons: A situation where individuals, acting independently and rationally according to their own self-interest, will ultimately deplete or destroy a shared resource, even when it is not in anyone's long-term interest for this to happen.
Collective Goods: Goods or services that are non-rival and non-excludable, meaning that one person's consumption of the good does not reduce the amount available to others, and it is difficult to exclude people from accessing the good.