Botrytis, a genus of fungal plant pathogens, is the focus of intensive scientific research worldwide. The complex interactions between these pathogens and the plants they infect (referred to collectively as the pathosystem) and the economic importance of the diseases caused by Botrytis on more than 1400 species of cultivated plants, many of which are important agricultural crops, render this pathogen of particular interest to farmers, agriculture experts, advisers, extension staff, students and researchers worldwide. This book is the product of intensive work by 41 authors, all of whom are leading scientists from various scientific disciplines studying Botrytis as a fungus and as a pathogen. The authors of this book have amassed state-of-the art knowledge on diverse topics, including Botrytis epidemiology, disease management, biological and chemical control and aspects of the plant-pathogen interactome, including virulence factors and defense processes, signaling cascades, the oxidative burst and general biological aspects, such as vegetative incompatibility, mycoviruses, and the revised Botrytis species concept. This book also provides reviews of the genetic and post-genomic analyses, such as transcriptomics and proteomics, used to study Botrytis biology and pathogenicity. This 20-chapter book is a comprehensive treatise covering the rapidly developing science of Botrytis and reflecting the major developments in studies of this fungus. It will serve as a source of general information for specialists in agriculture and horticulture, but also for students and scientists interested in the biology of this fascinating, multifaceted phytopathogenic fungal species.