Every designer wants to know what makes a product or process optimal. This book suggests a holistic approach to optimization that involves two steps: find a set of trade-off optimal solutions involving two or more conflicting objectives related to the problem, and then analyze these high-performing solutions to determine solution principles that commonly prevail among these solutions. Since the solutions are optimal, such common principles are likely to exist; and since these principles are common to many solutions they are likely to provide robust, reliable solution principles. The author is one of the leading researchers in multiobjective optimization, and an expert in design methodology. In this book he offers introductions to innovation in design; multiobjective optimization, in particular evolutionary multiobjective optimization (EMO) techniques that find multiple, trade-off, optimal solutions; and knowledge extraction from multivariate data using graphical, regression and clustering techniques. He then introduces his innovization methodology for revealing new, innovative design principles related to decision variables and objectives, and he demonstrates it through engineering case studies, in particular product and process design problems. The book will be of benefit to practitioners, researchers and students engaged with issues of optimal design, in particular in domains such as engineering design, product design, engineering optimization, manufacturing, process design and complex systems. The sample computer code referenced is available from the author's website.