The shape of the online universe. This image shows the hierarchical structure of the Internet, based on the connections between individual nodes (such as service providers). Three distinct regions are apparent: an inner core of highly connected nodes, an outer periphery of isolated networks, and a mantle-like mass of peer-connected nodes. The bigger the node, the more connections it has. Those nodes that are closest to the center are connected to more well-connected nodes than are those on the periphery.