This book is an overview and essence of the fundamental theory, effect mechanisms, and frontier applications of lasers’ interaction with matter, showcasing lasers’ cutting-edge achievements in areas such as precision manufacturing, rapid cleaning, environmental protection, and laser system component applications. It mainly covers femtosecond laser characteristics and processing advantages, laser and plasma cleaning, plasma spectroscopy for interface detection, and laser-induced damage to optical materials. This book starts from the basic principles of laser’s interaction with matter, carrying out theoretical analysis, mechanism research, simulation modeling, experimental verification, and the establishment of corresponding physical models on the laser action process and effects with regard to different laser parameters and material types.