For all the interest that wireless sensor networks (WSNs) have created over the past decade, there are few examples to show that they are truly delivering on this promise. What is missing? Deviating from the usual focus on routing and energy efficiency, this book explores the path from conceptual development to actual applications. It gives examples of what applications of WSNs could look like, identifies constraints, and highlights lessons learned from existing applications. Throughout, this book challenges your thinking about how to design a WSN application.