What is the light amplification by stimulated emission of radiation?

Answer 1

That is the original meaning for LASER. Light is increased in magnitude by increasing the number of electrons jumping into a lower energy state The light emitted from this process is concentrated and focused

Answer 2

Light amplification by stimulated emission of radiation (LASER) is a process in which light is generated by stimulating atoms or molecules to emit photons in phase and in the same direction. This results in a coherent and concentrated beam of light. Lasers are used in a wide range of applications, including in technology, medicine, and research.