The researchers describe the Internet as being like a jellyfish because they found that it has three layers. Forming the core are the 100 or so most tightly connected subnetworks, including groups such as Google and AT&T Worldnet. The rest of the jellyfish's body consists of a much larger group of subnetworks that are highly connected to one another and to the core. The remaining subnetworks, about 20 percent of the total, can communicate with the outside world only by passing information through the core. They form the jellyfish's tentacles.
