flash

The high-speed wing action of a hummingbird hawk-moth is frozen by flash. The flash has given the foreground more illumination than the background. See Inverse-square law. Video demonstration of high-speed flash photography

A flash is a device used in photography that produces a brief burst of light (lasting around 1⁄200 of a second) at a color temperature of about 5500 K to help illuminate a scene. The main purpose of a flash is to illuminate a dark scene. Other uses are capturing quickly moving objects or changing the quality of light. Flash refers either to the flash of light itself or to the electronic flash unit discharging the light. Most current flash units are electronic, having evolved from single-use flashbulbs and flammable powders. Modern cameras often activate flash units automatically.