Most of the inustrialized world is lit by electric lights, which are used both at night and to provide additional light during the daytime. These lights are normally powered by the electric grid, but some run on local generators, and emergency generators serve as backups in hospitals and other locations where a loss of power could be catastrophic. Battery-powered lights, usually called "flashlights" or "torches", are used for portability and as backups when the main lights fail.