The engineering necessity of fracture mechanics is to improve the empirical data-handbook style and mechanics of materials based design. This book examines the phenomenon of "crack growth". The contributed chapters in this book have been derived from various research groups' results from their experiments and/or simulations of crack growth in various media. The contributed chapters discuss the effect of inhomogeneity, plasticity effects in single crystals, interfaces and welded joints. The book gives a snapshot of the research effort of various groups around the globe in the past decade or more on the important topic of crack growth.