Economics term. A resource is said to be "nonrival" when consumers do not have to compete for it. For example, the familiar public field where locals graze their livestock in the
Tragedy of the Commons is a rival resource: if my livestock are grazing, yours cannot be. However, the tragedy of the commons is only a tragedy when the public resource in question is a
rival resource. Digital resources available over the network are truly nonrival: if I am viewing an image of the
Mona Lisa online, several other people can view it simultaneously (unless the site is being
slashdotted).
The broad availability of nonrival resources led
Dan Bricklin to coin the phrase the
Cornucopia of the Commons. In many
P2P systems like
Napster, "consumption" of nonrival common goods simply creates more of them, as (in this example) users who download an
mp3 now make an additional copy of the resource available to system users. Truly nonrival, broadly available resources came into existence with the
internet itself, and have a profound potential for transforming society, especially when paired with the notion of
opencontent.