By definition, a "public good" is one that is not traded on a market
             like a private good; it has no competition per se, and is often non-
             excludable in consumption. Public goods have two key factors which are its
             cost is indivisible, making it have a marginal cost of zero, and it is not
             A public good that is under-produced, could be, for example, no-
             commercial public radio. As there are no-commercials, it is essentially a
             not-for-profit good because anyone with a radio can tune into it and are
             not charged for its use, and it has a marginal cost of zero. Two people can
             enjoy the same station, at the same time. Commercial-free radio is under-
             produced because of the cost factors placed on the provider of the service.
             They rely on charitable means to receive funding which makes it difficult
             for them to survive against commercial radio stations.
             A public good that is over-produced on the other hand, could be
             congested bridges. Argumentatively, this is an under-produced public good
             that has turned over-produced due to the nature of a public good. This is
             to say, a congested bridge has fallen victim of what makes it a public good
             - the free ride' effect has taken place and while people are trying to use
             it at the same time, it has minimal funding to keep it from being
             congested. This kind of over-produced public good has fallen into a catch-
             22 because it is trying to remain a public good, but clearly needs extra
             ...