The flow of on-line information in global networks

One of the most effective early metaphors for on-line information was to think of the Web as an enormous universal library, with search tools crawling and indexing the content, and users issuing queries based on their information needs. In the past several years, this metaphor has been supplemented by an alternate and equally powerful view — a view that underpins the discovery and sharing of content via blogs, messaging, and Twitter — in which information reaches us continuously in small increments from real-time sources, conveyed largely through our social networks. Here we focus on this real-time view of on-line information, asking what types of principles are most relevant for designing and analyzing applications in this context. To understand the dynamics of real-time information, we need ways of reasoning about how information moves between people through social networks. We also need to think about the small fragments of information themselves — the links, references, and bits of text that travel through these networks, periodically mutating and combining with each other as they travel. We illustrate these issues by focusing on several recent lines of work. The ease with which information can travel from person to person is based in part on underlying mechanisms of social influence [10, 22, 23], by which individuals have an increased likelihood of engaging in a behavior when their neighbors in a social network are doing so. More