Colour temperature is the combination of the three primary colours: red, green and blue, (identified as RGB channels by an SLR camera) that are found in all light sources.
Colour temperature is measured in Degrees Kelvin. A low Kelvin number such as 1000 will have a warm colour temperature. A higher number such as 10,000 will be much cooler in colour.
Colour temperature contributes to colour balance. Photographs that are imbalanced in colour usually have:
1) A loss of colour that leads to a flat or dull image.
2) Colour inaccuracy where the true colours that were at the scene are not reflected and reproduced properly in the final image.