The authors provide an excellent overview of conjugation effects in organic chemistry within and between Pi systems. Besides various aspects of aromaticity one finds detailed discussions of homo-, spiroand hyperconjugation as well as effects of through-space and throughbond interactions. These effects are presented on the basis of experimental results and are analyzed by the use of qualitative arguments of perturbation theory and from a comparison with results from high level ab initio calculations. This book is a must-have for bachelor students from the second year on, master and PhD students of chemistry. Also students in science such as physics, biology and medicine will benefit from the concepts described in the book. Furthermore, chemists in research and development will be grateful to find here an overview of conjugation effects allowing to understand the structures, the dynamics and the reactivity of molecules.