With blockchain underpinning cryptocurrencies and improving IoT security, this book uncovers the evolution of blockchain (1.0 to 4.0) and its applications. It also introduces AI, discussing its development, paradigms, and industry-wide impact. The book explores the integration of cryptography, blockchain, and artificial intelligence (AI) in areas such as big data, bioinformatics, IoT, 5G, and Industry 4.0. It highlights how these technologies drive the digital revolution, enabling multi-agent systems, autonomous models, and enhanced security.