This book explores the essential knowledge of fatigue and fatigue failure, emphasizing its importance in the areas of mechanical engineering and structural engineering. Covering fundamental understanding of fatigue to its practical applications, this book provides comprehensive insights that can be readily applied in practical engineering problems. Rather than presenting textbook-like content on fatigue, the authors provide easy-to-understand and practical content for both general engineers and students. Moreover, they introduce the latest research findings and useful information, facilitating rapid acquisition of fatigue-related knowledge. Particularly, sections requiring expertise in fracture mechanics are minimized, ensuring easy comprehension even for readers without specialized knowledge. Designed for use in advanced undergraduate or graduate-level courses, this book is highly recommended for engineers looking to help design and management based on a holistic understanding of fatigue.