This book offers a practical and accessible guide to mechanics, material science, and design engineering, using real-world accident cases to illustrate key principles. It examines past accidents involving bolted joints, exploring mechanical failures, root causes, and corrective measures. It also covers essential topics, including mechanical analysis, initial tightening techniques, and fundamental design methodologies, followed by advanced discussions on strength design under axial, bending, transverse, and torsional loads. Additional chapters address loosening mechanisms, prevention strategies, and threaded joint applications in pipe fittings, along with insights into delayed fracture mechanisms, fretting fatigue countermeasures, and emerging fastening technologies. The book also provides an overview of international screw fastening standards, including ISO, JIS, and VDI 2230.