Examples of public goods are not as rare as one might expect. A flood control dam is a public goods. Once the dam is built, all persons living in the area will benefit-irrespective of their own contribution to the construction cost of the dam. The same holds true for highway signs or aids to navigation. Once a lighthouse is butt, no ship of any nationality can be effectively excluded from the utilization of the lighthouse for navigational purpose. National defense is another example. Even a person who voted against military expenditures or did not pay any taxes will benefit from the protection afforded.