Due to the rapid progress in laser technology a wealth of novel fundamental and applied applications of lasers in atomic and plasma physics have become possible. This book focuses on the interaction of high intensity lasers with matter. It is currently the first book reviewing the whole field of intense laser field physics. The book reviews the state-of-the-art of high power laser sources, intensity laser-atom and laser-plasma interactions, laser matter interaction at relativistic intensities, and QED with intense lasers. It gives a broad basis and the background material for grad students and researchers from related areas and serves as a reference work for experts.