This book deals with the most important aspects of software diversity and its use in computerized control systems, including theoretical background, experiments, and industrial realizations (railway, flight and nuclear applications). Researchers describe their experiments with software diversity and explain their results, including benefits and drawbacks. Practitioners explain their use of it in real systems: why they use this means of fault-tolerance, and how they incorporate it into their systems. In addition to the papers the book contains a rather complete list of publications giving an overview on references about software diversity from its beginning until today. Therefore, this book is a complete description of the state of the art on the topic of software diversity.