What is a Laser / Lasing?

Laser (an acronym for “Light Amplification by the Stimulated Emission of Radiation”) is a device that creates uniform coherent light. Many lasers deliver light in an almost-perfectly parallel beam (collimated) that is very pure, approaching a single wavelength. Laser light can be focused down to a tiny spot as small as a single wavelength, or re-focused to spread across a larger area.

Lasing is a verb describing the generation of light in a laser.