In order to function properly and to avoid death, a cell's life relies upon energy deposits, conversion, utilization and exchange. Over 200 years of study tells us how cells convert biological fuels into usable energy. This process is broadly known as bioenergetics which has generated traditions in describing origins of life, metabolism, ecological adaptation, homeostasis, aging and various other life processes. This book discusses some of these traditions via chapters contributed by international experts. Both beginners and professionals will find this book benefiting in linking scientific revolutions in the fields of organism biology, membrane physiology and molecular biology to enhance the subject of bioenergetics towards solving contemporary and future difficulties in metabolic diseases, life transitions and longevity, and performance optimization.