Laser stands for light amplification by stimulated emission of radiation. A laser is any device that emits a narrow beam of light at a particular wavelength by stimulating atoms and molecules using electromagnetic radiation. Various components of a laser beam device are gain medium, high reflector, laser pumping energy, laser beam and an output coupler. A laser beam profiler is used to measure the depth, divergence and intensity profile of laser beams. Lasers are highly coherent in nature. This allows them to stay focused in a tight spot, making lasers an excellent choice for use in various domains such as printing, welding, cutting, photolithography, weapons, fiber optics, DNA sequencing, etc. Lasers are of various types such as solid-state lasers, gas lasers, dye lasers, semiconductor lasers, etc. Use of laser in medical treatments such as laser hair removal, laser mammography is known as laser medicine. Lasers are used in either continuous wave operation or pulsed operation. This book elucidates the concepts and innovative models around prospective developments with respect to lasers. This book is compiled in such a manner, that it will provide in-depth knowledge about the theory and practice of lasers. Coherent flow of topics, student-friendly language and extensive use of examples make this book an invaluable source of knowledge.