Fatigue is progressive and localised structural damage that occurs when materials are subjected to cyclic loading. Therefore, in order to produce durable products against fatigue and to prevent catastrophic failures it is essential to develop feasible fatigue design methods as well as understand the fatigue phenomenon and its micro-mechanisms. This book covers leading-edge research on fundamental areas of fatigue. The topics addressed include reliability-based design techniques, fatigue life prediction approaches, damage-tolerant design for thermo-mechanical fatigue, fatigue crack growth rate models, fatigue behaviour of short cracks, and microstructure and geometric effects.