A Laser is a illuminating device that emits electromagnetic radiation through a process called stimulated emission. The term "laser" is actually an acronym for Light Amplification by Stimulated Emission of Radiation. Laser light is almost always spatially coherent, which means that the light is either emitted in a narrow, low-divergence beam, or can be converted into one with help from optical components, such as lenses. Usually, lasers are thought of as emitting light with a narrow wavelength spectrum ("monochromatic" light).