> In economic terms, intellectual property is non-rival, whereas tangible property is rival. As a result, the “piracy” of intellectual property is simply not the same sort of zero-sum game that car theft — or theft of any tangible property — is. And that means that when Hollywood or the U.S. government says that music or movie downloaders are “pirates” or “thieves,” they are indulging in a bit of loose rhetoric. There are, in general, good moral reasons not to take what doesn’t belong to you. But as this video by filmmaker Nina Paley so beautifully illustrates, copying is not theft.
Source: http://freakonomics.com/2012/04/02/copying-is-not-theft/