This book provides an up-to-date knowledge on theory and experimental results of rate-dependent fracture processes in metallic materials. The objective is to expose the current status of a growing branch of fracture mechanics called generally “Dynamic Fracture”. Crack dynamics takes into account not only the effects of inertia but also rate sensitivity of a material under consideration. This volume has been prepared by four leading authorities in fracture dynamics: D.R. Curran, J.F. Kalthoff, J.R. Klepaczko and F. Nilsson. A broad range of problem is covered: dynamic fracture theory, application of dynamic fracture mechanics, dynamic crack inition and microstatistical fracture mechanics in dynamic fracture. The book in its present format may serve as a text supplement in lecturing on fracture mechanics. On the other hand, it may serve as an instructional aid in engineering of fracture prevention.