The Web and Internet as complex networks
Figure 2. (a) The nodes of the World Wide Web are Web documents, each of which is identified by an unique uniform resource locator, or URL. Most documents contain URLs that link to other pages. These URLs represent outgoing links, three of which are shown (blue arrows). Currently there are about 80 documents worldwide that point to our Web site, represented by the incoming green arrows. While we have complete control over the number of the outgoing links, kout, from our Web page, the number of incoming links, kin, is decided by other people, and thus characterizes the popularity of the page. (b) The Internet itself, on the other hand, is a network of routers that navigate packets of data from one computer to another. The routers are connected to each other by various physical or wireless links and are grouped into several domains. (c) The probability that a Web page has kin (blue) or kout (red) links follows a power law. The results are based on a sample of over 325 000 Web pages collected by Hawoong Jeong. (d) The degree distribution of the Internet at the router level, where k denotes the number of links a router has to other routers. This research by Ramesh Govindan from University of Southern California is based on over 260 000 routers and demonstrates that the Internet exhibits power-law behaviour.