These developments have led to an emerging study of complex networks, and a range of interesting research challenges. We are beginning to discover that large networks have a characteristic `geography'; they share a number of fundamental structural properties that presumably reflect the forces driving their growth and evolution. We are only beginning, however, to formulate models for the way in which such properties might arise. The interplay between structure and content in these networks adds a further dimension to this investigation, providing a means for understanding a large corpus like the Web through its underlying network topology.