Blue light is a color in the light spectrum visible to human eyes — though it doesn’t actually appear blue to the naked eye.
It's a short wavelength that produces high amounts of energy (from 400 to 500 nanometers) and is often referred to as high-energy visible light (HEV). In fact, any source of visible light emits blue light, whether it's an artificial source like a digital screen or a light bulb, or a natural one, like the sun.