In its modern usage, the phrase is used as a metaphor to the above, referring to the exploitation of a common resource. In game theory it is used as an example of how, in a given situation, every individual can choose to do what is best for their own interests and still produce the worst sum result for the whole. See also: prisoner's dilemna.
The most common and effective way to negotiate this problem is private ownership. Another way is heavy regulation and the imposition of sanctions on violators.
Everyone feels they have the right to consume because they are part of the public, but no one feels it their responsibility to maintain it because they are not individually accountable.
Commonly used to argue that having any resources (parks, etc.) held in common will always lead to their destruction. Especially by libertarians and people who want corporate welfare.