When we look at something, our eyes are cleverly able to ‘correct’ the colours in different lighting conditions, so whether you look at the same red cup indoors or out, its colour will most likely remain unchanged. However, photographic films can’t adjust in the same way, and that’s why different films exist for different light conditions. Most films on the market today are daylight balanced, which means they are designed to give you accurate colours outdoors or under electronic flash conditions (usual daylight is about 5500 kelvin – a kelvin is a unit of measure usually used for light temperature).
On the other hand, tungsten film was originally introduced to give accurate colours for photographers who shoot indoors under studio light conditions. Tungsten lights (such as photofloods) have a much lower colour temperature than daylight (about 3200 kelvins). If a daylight corrected film is shot under tungsten light conditions, it often produces a yellow-orange hue. Tungsten film will give a neutral colour balance under tungsten lighting conditions. By the way, tungsten is another name for the chemical element wolfram, a metal which is often used in light bulb filaments.
So should tungsten film be shot exclusively under tungsten light conditions? The answer is no. As Lomographers, we like to forget the rules. Shoot it indoors or out, under tungsten lighting or daylight conditions (just remember to bear in mind its low ISO), throw the tungsten rulebook out the window and experiment in whatever conditions you like!