The color of light, expressed in Kelvins (K). The sun is about 5800 Kelvins. This is called a "temperature," because the hotter fire gets, the more it changes from a warm yellow glow to white.

There are a lot of technical terms that get used in TV marketing these days, but none is more mysterious than colour ...

Color-changing phones aren't anything new, but how about a phone that changes color based on your environmental temperature?