A flashlight is a portable hand-held electric light. The source of the light is usually an incandescent light bulb or light-emitting diode. A typical flashlight consists of the light source mounted in a reflector, a transparent cover and sometimes combined with a lens to protect the light source and reflector, a battery, and a switch. These are supported and protected by a case.
source: https://en.wikipedia.org/wiki/Flashlight