1 Principles of Lasers and Laser-Surface Interactions. 1.1 Introduction. 1.2 Basics of Lasers. 1.3 Continuous and Pulsed Modes of Operation of Lasers. 1.4 Coherence of Light. 1.5 Modification of Surface Properties. References. 2 Interaction of Low-Power Laser Radiation with Surfaces. 2.1 Laser Rangefinders. 2.2 LIDAR. 2.3 Holography. 2.4 Low-Level Laser Therapy. 2.5 Laser Interferometer Gravitational-Wave Observatories...