Communities – networks within networks

When the TCP/IP suite of telecommunication protocols was introduced in 1974, it suddenly became possible for computer networks using different hardware and software to communicate with one another—to internetwork—creating what we now know as the internet. On a related note, many of the approximately 13,000 proteins found in fruit flies interact with at least one other protein. Among these, smaller groups can be found in which each protein interacts with most of the others. It may not be immediately obvious what fruit flies have to do with the internet (aside from both being found on apples). The connection is this: as with many different kinds of networks, both the internet and protein interaction networks have smaller sub-networks with both internal structure and external relationships. In network science, these groups...