The book contains chapters written by leaders in the research on the structure and function of respiratory complex I. It will provide a concise and authoritative summary of the current knowledge on complex I of respiratory chains. This enzyme is central to energy metabolism and is implicated in many human neurodegenerative diseases, as well as in aging. Until recently it was poorly understood on a structural level, and this book will provide a timely reference resource. Such a book was not published previously. The last time a mini review series on complex I were published was in 2001, and since then complex I field changed quite dramatically.