A light tower is a piece of mobile equipment which has one or more high-intensity electric lamps and a mast. Almost always, the lights are attached to the mast, which is attached to a trailer, with a generator set to power the lamps. Normally the lamps are metal halide bulbs and the generator is powered by a diesel engine. However, battery-powered, solar-powered and hydrogen-powered sets are available; light towers with electrodeless lamps lighting are also sold. Modular kits permit separation of the generator set, trailer, lights and mast from each other. Another variation is an inflatable mast.[1] Particularly when an inflatable mast is used, the lights may be placed close to the ground, with a reflector attached to the mast.[2] When soft lighting is wanted, an inflatable “balloon” diffuser may be used. An inflatable mast may serve as a diffuser.

Light towers are used for construction. Some purveyors promote their use for other activities where strong, temporary, outdoor illumination may be wanted, such as mining, motion picture production, demolition,[3] emergency services, oil refining, sport or agricultural sectors.