In 1999 Shawn Fanning, an 18-year-old at Northeastern University, develops Napster: the first mass-scale peer-to-peer file-sharing network, letting users share MP3s directly, though using a central index server. At its peak (2001) Napster had over 80 million users. The RIAA sues; a 2001 federal court orders its shutdown. Napster reveals P2P's ability to distribute content globally, and the fragility of its centralized index — a lesson that inspires Bram Cohen's BitTorrent (2001) and shapes Satoshi Nakamoto's conceptual horizon for Bitcoin (2008).