This book describes the thermal and hydrodynamic instabilities appearing in laser-matter interactions at moderate intensities. These instabilities result in the distortion of phase-transition front, dispersion of target material in condensed phase, formation of dissipative surface structures, generation of complex oscillatory evaporation modes, and so on. These effects, in turn, lead to the appearance of liquid droplets in an expanding vapor, non-uniform removal of a solid material, and the enhanced light absorption in the vapor plume.This book focuses on nonresonant interactions. It concentrates on the range of low and moderate laser intensities that are important for technological applications of lasers.Instabilities in Laser-Matter Interaction provides a theoretical background to the interpretation of experimental results and an understanding of the effect of instabilities on the processes of laser technology.