From the beginning of history, humanity has a need for portable light sources. Torches, candles, oil lamps and kerosene lamps were designed to be carried around but they could be dangerous because they have flame as a source of light. Inventions of incandescent electric light bulb and of dry battery at the end of the 19th century enabled solution for this problem.
First dry cell batter was invented in 1896. It was an improved variant of the previous version in that way that its electrolyte was a paste instead of liquid. Because of that, it could work in any position and it would not break or spill that easily. It was a perfect power source for a portable light source. In 1899, English inventor David Misell invented the first flashlight. It had three D batteries placed in a tube that acted as a handle of the device. Batteries powered a small incandescent electric light bulb and a simple contact switch turned light on and off. They were called “flash” lights because they could not throw light for too long and you had to turn them off to “rest” them from time to time because early flashlights run on zinc-carbon batteries that could not give constant current for a longer periods of time. First flashlights did not sell too well because of the behaviors of batteries and because carbon-filament electric bulbs were inefficient. Replacing of carbon filament with tungsten and improving of batteries made flashlight a more useful device, which increased its popularity and it started to replace lamps with flammable fuel. By 1922, there were several different designs of flashlights. There was classic cylindrical variant, a lantern-shaped version that could be left to stand, reflector type for lightning a greater area and a small pocket variant. Different varieties and usefulness were reasons of the high demand, which resulted in 10 million flashlight users by the same time.
Modern flashlights generally have the same or similar parts and work basically the same. They most commonly use incandescent light bulbs or LEDS. Incandescent light bulbs have tungsten filament in a glass bulb in atmosphere of vacuum or of gas xenon, argon or krypton; noble gases that reduce evaporation of filament and with that make lamp last longer. Light Emitting Diodes (LEDs) are electronic elements, semiconductors that emit light. Types that are used in flashlights are of white high-power kind. They are much more efficient than incandescent light bulbs and last longer. As a source of energy, they mostly use batteries but the can use accumulators or super-capacitors, they can be charged by solar power or mechanically. Depending on planed use they are made in myriad of shapes. They are made like keyrings or pens, as headlamps on helmets, with clips for mounting on rifles and as high power reflectors. We have them on mobile phones and in hundreds of variants more.
Flash light is an object that basically started as a novelty and turned into a necessity with thousands of possible uses. Pretty impressive.