Blockchains

This book takes readers into the history of blockchains to explain the phenomenon that has taken the world by storm. Underpinned by blockchain technology, Bitcoin created a peer-to-peer system that single-handedly brought cryptocurrency into the mainstream and renewed interest in decentralized database systems. The book explores decentralized systems, which have no single owner and build robustness through all the stakeholder contributions. Blockchains can be used to build trust into existing systems, thus they present an attractive solutions in many different domains, spanning both academia and industry. Despite this potential, high-impact, real-world applications of blockchain have not been realized outside of cryptocurrencies. The book explores what the fundamental, technical limitations that may be preventing blockchain from realizing its full potential. Setting out to demystify blockchains through the lens of database systems, the book first capitalizes on databases as extensively researched and field tested for many years, using database concepts to explain blockchain systems to allow for deeper understanding of the latter. Secondly, the book utilizes the connection between databases and blockchains to emphasize the focus on the block, which is a general platform for blockchain rather than one that is specifically designed for cryptocurrencies. As a novel data system, blockchain has the potential to disrupt many industry sectors, just as databases did decades ago. Readers who are completely new to blockchains will find this book useful as it contains a comprehensive survey of the state of the art. Readers who have some experience with blockchains, for example from using or developing cryptocurrencies, may find the book's database perspectives enlightening. Finally, researchers working in the blockchain space will be able to appreciate the design space and the subtle differences with state-of-the-art databases; they will be able to identify gaps in the space and explore potential solutions that create next-generation blockchain systems.