BitTorrent thus demonstrates a key Web 2.0 principle: the service automatically gets better the more people use it. While Akamai must add servers to improve service, every BitTorrent consumer brings his own resources to the party. There's an implicit "architecture of participation", a built-in ethic of cooperation, in which the service acts primarily as an intelligent broker, connecting the edges to each other and harnessing the power of the users themselves.
web 2.0 in a nutshell: network effect