LASER is an abbreviated form of "Light Amplification by Stimulated Emission of Radiation". It is an instrument which produces coherent and monochromatic light beam, which is uniform in nature and can be focused to very small and far off objects as well. Laser produces either pulsed or continuous output and has a number of applications in various fields.
There is an important phenomena related to LASER called 'Population Inversion' which has been described below....