8About the book.Distributed ledgers and blockchains are much older than Bitcoin. A sizeable amount of work in distributed systems and cryptography is about storing transactions securely. The area is central in computer science, about half of all Turing Awards (known as the "Nobel Prize of Computing") of the last decade can be linked to distributed ledgers. This book will give a scientifically precise description of the most interesting approaches that have emerged, before Bitcoin and after. Whether you are interested in permissioned or permissionless blockchains, this book will help to get a deep understanding. This book introduces the basic techniques when building fault-tolerant distributed systems, discussing various protocols and algorithms that allow for fault-tolerant operation, and practical systems that implement these techniques. .About the third edition.Apart from many minor improvements, this third edition of the book contains a lot more content. In particular, the third edition includes new chapters and sections on broadcast, shared coins, selfish mining, DAG-blockchains, payment hubs, proof-of-stake, strong consistency and logical time. In addition, the book features an appendix, discussing some of the underlying fundamentals such as game theory, physical clocks, and Markov chains..About the author.Roger Wattenhofer is a professor at ETH Zurich. Before joining ETH Zurich, he was at Brown University and Microsoft Research. His research interests include fault-tolerant distributed systems, efficient network algorithms, and cryptocurrencies. He has published more than 300 scientific articles.