In its simplest form, a network is a collection of points, or nodes, joined by lines, or edges.
As purely theoretical objects, networks have been the subject of academic scrutiny since at least the 18th century. But they have taken on a new practical role in recent years as a primary tool in the study of complex systems—real-world systems of interacting components, for which networks provide a simple but tremendously useful representation. 1 The internet, for example, can be represented as a network of computers linked by data connections. The World Wide Web is a network of information stored on webpages and connected by hyperlinks. Social networks of friendships between individuals have received a lot of recent attention, and other kinds of social networks, such as those of professional or business contacts, are also attracting their share of interest. Biological networks, such as the interrelated metabolic reactions that run the...
