This book is a must-have for blockchain developers who want to learn from scratch how to leverage blockchain technology in a real-world setting.  The first section provides a brief overview of blockchain technology, including its concepts, history, technology genre, major related companies and typical application scenarios, and presents an ecological map for the blockchain industry by comparing and analyzing some mainstream platforms. The second section systematically introduces Ethereum and HyperLedger, exemplars of well-known open-source blockchain platforms, and demonstrates how to conduct blockchain applications development based on the two platforms. The third section illustrates core technology of enterprise blockchain platforms (to take Hyperchain, an independent, controllable blockchain alliance as an example), and covers Hyperchain based enterprise blockchain applications development technology. The fourth section presents 6 actual blockchain-based applications examples, and analyzes applications development procedure and related key codes. Examples in this book are of great practicability and operability, allowing practitioners to get started easily, and eventually utilize these skills to develop real-life, usable blockchain applications.