This book provides an in-depth introduction to hybrid DC-DC converters, which integrate both inductors and capacitors for high efficiency and high power density. These converters address the demands of applications like high-performance computing and automotive electronics. While numerous hybrid converter combinations have been explored in recent research, this book guides readers in selecting the optimal topology for a specific application. This book provides an incisive understanding of hybrid converters, revealing their underlying design philosophy. The authors present multiple examples of popular hybrid converters, tracing their evolution from simple, fundamental transformer models while  highlighting their benefits and limitations. Furthermore, the book includes design guidelines for inventing new hybrid converters.