The fast growth in world population and the associated energy requirements, the announced depletion of fossil fuel resources, the continuing rise in greenhouse gas emissions with the induced climatic changes represent some of the major challenges to be taken up in the coming years and decades. Hybridization, therefore, typically represents a transition technology that significantly improve the energy and environmental performance of current vehicles, without radically changing their use typologies, while opening the way to new propulsion modes for the longer term. It is nevertheless a complex subject requiring a multidisciplinary approach. This book, which is intended to be exhaustive, considers the vehicle, its components, their association, and their control, as well as the global balances determined over the vehicle lifetime. It starts with a general presentation of the various conditions of use of vehicles, to give readers an understanding of the stakes related to the development of hybrid vehicles and the methods used to compare the performance of the various solutions.