Much of the hubris and hyperbole surrounding the 1990s internet has softened to a reasonable level, but the momentum of information growth continues unabated. Although this wealth of information provides resources for dealing with the problems posed by our increasingly complex world, the availability of more information does not guarantee that it can be successfully transformed into valuable knowledge that shapes, guides, and improves our lives. When we try to use traditional research models to analyse what people do to make sense of the huge amount of information available on the web, they tell us a lot about learning and performance with browser operations, but very little about how people will actively navigate and search through information structures, what information they will choose to consume, and what conceptual models they will form about the landscape of cyberspace. Thus, it is fortunate that there is a new field of research, Adaptive Information Interaction (AII), that centres on the problems of understanding and improving human-information interaction. All is about how people will best shape themselves to their information environments, and how information environments can best be shaped to people. Its roots lie in human-computer interaction (HCI), information retrieval, and the behavioural and social sciences. This book is about Information Foraging Theory (IFT), a new theory in Adaptive Information Interaction. Information Foraging Theory is one example of a recent flourish of theories in adaptationist psychology that draw upon evolutionary-ecology theory in biology. IFT assumes that people are ecologically rational, and that human information-seeking mechanisms and strategies adapt the structure of the information environments in which they operate. Its main aim is to create technology that is better shaped to users.