A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The acronym laser stands for "light amplification by stimulated emission of radiation." A laser is a coherent and focused beam of photons; coherent, in this context, means that it is all one wavelength, unlike ordinary light which showers on us in many wavelengths. Many scientific, military, medical and commercial laser applications have been developed since the invention of the laser in 1958. There is a wide range of medical applications. Often these relate to the outer parts of the human body, which are easily reached with light; examples are eye surgery and vision correction, dentistry, dermatology, and various kinds of cosmetic treatment such as tattoo removal and hair removal. Lasers are also used for surgery, exploiting the possibility to cut tissues while causing minimal bleeding. Lasers are used for photocoagulation of the retina to halt retinal hemorrhaging and for the tacking of retinal tears. Higher power lasers are used after cataract surgery if the supportive membrane surrounding the implanted lens becomes milky. The highly collimated beam of a laser can be further focused to a microscopic dot of extremely high energy density for welding and cutting. The automobile industry makes extensive use of carbon dioxide lasers with powers up to several kilowatts for computer controlled welding on auto assembly lines. Helium-neon and semiconductor lasers have become standard parts of the field surveyor's equipment. Laser cutters are credited with keeping the garment industry competitive in the world market. Fiber optic cables are a major mode of communication partly because multiple signals can be sent with high quality and low loss by light propagating along the fibers. The light signals can be modulated with the information to be sent by either light emitting diodes or lasers. The lasers have significant advantages because they are more nearly monochromatic and this allows the pulse shape to be maintained better over long distances. This book deals with basic overview of physical phenomena on laser-matter interaction. The book presents of a number of laser applications in the nano-particles and thin films production, materials examination for industry, biological applications and long-range detection issues by LIDARs.