Networks are pervasive in the real world. Nature, society, information, and technology are supported by ostensibly different networks that in fact share an amazing number of interesting structural properties. The majority of these networks exist since many years, some of them (biological networks) are here since millions of years. The main common feature shared by these networks is that they are webs without a spider: there exist no central authority that regulates their growth, but they evolve in a self-organized and decentralized way.
Network science is a rapidly growing subfield of complexity science devoted to the holistic analysis of complex systems through the study of the structure of networks that wire their components.