Ever wondered what the heck 6500 Kelvin has to do with your photos? Here's an in-depth article from the blog of [James Duncan Davidson](http://duncandavidson.com/blog/) for better understanding of the whole color and white balance thing in photography.
[Measuring the Color of Light by James Duncan Davidson](http://duncandavidson.com/2008/04/kelvins-and-the-color-of-light.html):
> Like all settings, the color of light has a unit associated with it. The unit, however, isn't unique to specifying the color of light. Instead, it's the same SI unit that is used for temperature: the Kelvin. I know that the first few times I delved into this subject matter, I thought it was a strange unit to use, mostly because light itself doesn't have a temperature. Since it's radiation, when it hits a surface it can cause that surface to heat up. But the light itself is neither hot nor cold. So, why the heck is a unit of temperature used to describe the color of it? ...
And another in-depth article from James which is a follow up of the above article:
[Color Temperature and White Balance](http://duncandavidson.com/2008/04/color-temperature-and-sensors.html)
