In 2001 Bram Cohen designs BitTorrent, presented at CodeCon 2002, solving Napster's fatal flaw: central index dependency. BitTorrent splits files into fragments downloaded simultaneously from multiple sources and redistributed while downloading. Its tit-for-tat incentive mechanism rewards sharing with faster downloads, creating a self-sustaining system with no central authority. At its peak, BitTorrent represented 25-35% of all internet traffic. This model of a distributed system running correctly via crypto-economic incentives is the direct conceptual bridge to Bitcoin (2008).