How the 'Net works: an introduction to peering and transit

Page 1: "The story of how the Internet is structured economically is not so much a story about net neutrality, but rather it's a story about how ISPs actually do use AT&T's pipes for free, and about why AT&T actually wants them to do so. These inter-ISP sharing arrangements are known as 'peering' or 'transit,' and they are the two mechanisms that underlie the interconnection of networks that form the Internet."