This book addresses the growing need for security, reliability, and trust in modern digital ecosystems by presenting analytical models, experimental frameworks, and practical evaluation techniques. The contributions emphasize resilience and human‑centric considerations alongside technical defences.The novelty of this book lies in unifying cybersecurity, privacy, emerging technologies, and fault‑tolerant systems within a single, coherent perspective. Topics range from AI‑driven security and digital forensics to secure cloud infrastructures, dependable services, and technology adoption in critical domains.This book includes intrusion detection, privacy‑preserving systems, ransomware analysis, blockchain applications, smart city technologies, and reliable cloud and energy systems. This book targets academics, advanced students, and professionals seeking up‑to‑date references for research, teaching, and the design of robust, secure digital systems.