Natural white light consists of all visible wavelengths. This doesn't mean that all wavelengths are present with equal intensity, it only implies that the light isn't coloured, all colours or wavelengths are present in the spectrum. White or full the light usually has the same meaning. The term full spectrum is usually used with light bulbs. Its meaning isn 't technical because it isn't something we may measure or precisely define. It's more a marketing phrase that labels bulbs that reproduce natural light. Light from bulbs with such label is only less coloured than from regular bulbs. Which implies that virtually all visible wavelengths are present in the spectrum and for that reason the light is comparable to natural sunlight. Since of uneven spectral distribution some wavelengths or colours are present with higher intensity however this doesn't affect the final appearance. Each wavelength represents one color. For instance, red light has wavelength around 700 nm and violet around 400 nm. If you mix lights with all colours you get light with no colour or white light. Since such light contains all spectrum components from infrared to ultraviolet it's called full spectrum light. Some bulbs produce also significant ultraviolet components that are invisible, but the term is mainly related to visible wavelengths. Bulbs are marked with two technical parameters. The first one is colour temperature. This is equivalent temperature of the ideal black body which would radiate colour with the same hue as the source of light. The colour temperature is measured in Kelvins, this is an international unit for temperature. The old incandescent bulbs have colour temperature around 3000 K, their light is slightly yellow while light with higher colour temperatures is more blue or white. The daylight colour temperature is about 6500 K.Which implies that bulbs with this colour temperature will shine almost like sunlight. The 2nd parameter is colour rendering index. It's a measure of the capability to reproduce colours as they'd be reproduced with the ideal source of light. A reference source for colour rendering index is black body radiation with CRI 100, while bulbs which try to reproduce sunlight have CRI between 90 and 100. Bulbs with natural light are utilized in closed places where right colour reproduction is very important. Colors in the presence of light from this kind of bulbs may have the same hue as they'd have on daylight. Natural lighting is also used for the treatment of seasonal affective mood disorder. Despite numerous studies which didn't prove any benefits on mood or health, full spectrum lighting is becoming more and more prevalent selection.