The need to gain insight into data is common to many scientific and social disciplines. An effective way to facilitate insight is, first, to transform the (often numerical and confusing) data into representational images that are much easier to comprehend and which often lead to an "Ah Ha!" moment. There are many available representations ranging from the simple pie chart to those that are more comprehensive: a selection is illustrated by application to a variety of fields ranging from history to medicine, and the reason for their effectiveness analysed. But much greater insight into data is possible if a user can interact with its visual representation. To this end an effective framework for interaction design, Norman's Action Cycle, is introduced and illustrated using familiar examples: it is then applied to applications such as house purchase, web navigation, product design and involuntary browsing. An underlying concern of the book is with creative visual and interaction design.