Color temperature, or CCT (Correlated Color Temperature), specifies the color of the light that a light source generates.  Color temperature is measured in degrees Kelvin and, for normal applications range from 3000K to 5000K.  The lower the number the warmer (more yellow) the color temperature and the higher the number the cooler (more blue) the color temperature. An incandescent lamp has a color temperature of 2700K and noon sunlight is considered to be 5000K.  Ttypical offices have been lit with a 4100K fluorescent bulb for years.  The color temperature can help set a mood or a feel for a space.  If a customer wants a warm feeling, these types of spaces are typically lit with 3000K sources.  If the space is modern or clean, they are typically lit with 4000K or 5000K sources.

Many customers mistake color temperature with the quantity of light that a source puts out.  They may say something like “I want it to be as bright as possible, so 5000K would be good.”  The color temperature affects the light output of LEDs, but not by much.  You can have a 3000K source that puts out just as much quantity of light as a 5000K source.  The difference will be the color of the light.