Understanding Interactivity explains what interactivity is, how it works, why it's important, and how to design good software and websites that are truly interactive. Addresses important and timely issues regarding programming, design, and computing in general and offers insight into the process of designing interactivity which underlies all computer applications. Rules for the design of successful interactive applications and also included. The author's colloquial, conversational style makes it easy to grasp the fundamentals and theoretical underpinnings of interactivity.