Flashes & on camera lighting
A flash is a device used in photography producing a flash of artifical light (typically 1/1000 to 1/200 of a second) at a of about 5500K to help illuminate a scene. A major 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.
Studio equipment generally falls into one of two categories: strobe and continuous lighting. Those light sources are used in both studio and outdoor photography. Also, sometimes photographers use a combined setup when strobe and continuous light complement each other.