This book systematically studies blockchain adaptability and scalability, combining theoretical analysis with practical implementation. The book provides a comprehensive exploration of blockchain adaptability and scalability solutions through six chapters. Chapter 1 introduces blockchain overviews and current scalability challenges, emphasizing the need for adaptive and scalable blockchains. Chapter 2 systematically reviews consensus protocols, from classical BFT to modern PoW, PoS, and sharding approaches, setting the theoretical foundation for subsequent chapters. Chapter 3 presents AdaptPoW, which enhances PoW blockchain adaptability and scalability through dynamic structure adjustment and efficient transaction processing. Chapter 4 presents AdaptPoS, a PoS-based system with role decoupling and filter mechanism, enabling dynamic throughput adjustment while maintaining security. Chapter 5 describes AdaptShard for sharding-based blockchains, including its transaction allocation and optimistic processing strategy for cross-shard transactions. Chapter 6 concludes with insights and future research directions.