this paper, Gnutella is no exception to this finding, and an experimental study of its user patterns shows indeed that free riding is the norm rather than the exception. If distributed systems such as Gnutella rely on voluntary cooperation, rampant free riding may eventually render them useless, as few individuals will contribute anything that is new and high quality. Thus, the current debate over copyright might become a non-issue when compared to the possible collapse of such systems. This collapse can happen because of two factors, the tragedy of the digital commons, and increased system vulnerability, which we now discuss