Colour temperature is measured in degrees Kelvin and is the measure of the part of the colour spectrum that is found in light.
2700k – Warm White – similar to Incandescent and gives a warm yellow glow
3500k – Standard White colour or florescent T5 or 2D Lamps
4000k – Cool white gives a clean white light ideal for bathrooms and kitchens
6400k – Daylight Slightly bluer light ideal for detailed work applications