This book presents a novel approach by decoupling the various modules of sharding blockchains and providing detailed insights into the functions and design methodologies of each key module. Previous sharding blockchain solutions suffered from tight coupling between functional modules, making it challenging to achieve optimal security, performance, and scalability. Building upon this foundation, the authors present a universal composable method for composing sharding blockchains in a flexible manner. Additionally, the authors propose a novel shard member configuration method that leverages proof-of-work and verifiable distributed randomness to guarantee that each shard maintains a sufficient proportion of honest nodes, preventing it from falling below the safety threshold. Furthermore, the authors offer a complete design methodology for creating secure and scalable sharding blockchains. This includes reducing the complexity of intra-shard transaction processing through aggregation-supported multi-signature. The authors ensure optimal sharding of computational, communication, and storage resources within a formal security framework. To facilitate flexible cross-shard transaction processing, the authors introduce a new cross-shard Byzantine fault tolerance protocol. Lastly, the authors explore practical applications of sharding blockchains in typical scenarios. In the context of zero-trust cloud-edge-end scenarios, the authors demonstrate how sharding blockchains enable scalable data cross-shard sharing. Simultaneously, the authors design a secure and universally applicable cross-domain device authentication scheme.