Light sources all have a colour temperature which will dictate whether the light emitted is either of a warm colour, an intermediate or neutral colour, a cool colour, or a cold colour. The higher the colour temperature, the cooler, the colour appearance of the light source. The colour temperature is a description of the warmth or coolness of a light source. It is most simply, a method of demonstrating the colour characteristics of light, usually either as warm (yellowish) colour or a cool (bluish) colour.
This is measured in kelvins (K).

Warm white – 2000-3000K
Cool white – 4000-4500K
Daylight – 6000-6500K
There are some simple design “rules” to help! Generally, warmer colours of around 2700K to 3000K are seen as being welcoming and suitable for spaces of relaxation, The more intermediate colour of around 3500K, which are termed as being white, will create a neutral light appearance for a well-balanced environment. The cooler colour, around 4000K, provides a clean and stimulating environment offering the ideal solution for commercial office lighting and in many industrial working environments, whilst also giving that modern look within some residential situations, such as the kitchen. The colder colours towards daylight, at around 5000K and above, offer an enhanced clean and stimulating environment, where people need to maintain focus and stay alert over long periods of time