A: One critical difference between the Web and TV is how they scale. TV scales nicely—it costs the same to air a show to 10 viewers as it does to a million. On the Web, distributing a file to a million users at once is nearly a million times as costly (and slower) as delivering it to one.


BitTorrent, an open-source peer-to-peer parallel downloading tool written by Bram Cohen, changes the equation: The more popular a file is, the easier it becomes to fetch and the cheaper it becomes to serve.