In deciding whether a good is a public good, one must determine the excludability of the good.
A public good is a good or service that is provided to economy and all of the members within without profit. This good is given out by the government or an individual organization. An excludable good is a good that is able to be prevent of use by people who haven't paid - like a concert in an open arena, people who haven't paid for the concert can still hear the concert outside. Versus, a concert that is held inside an arena that's closed off, non-paying consumers cannot enjoy it.
