What is “color temperature”? What does "blue-white" and "warm-white" light mean?

Our lights are either 5000K or 3000K. The letter K stands for Kelvin, which is the unit of measurement used to define the color spectrum of visible light.  This is also called “color temperature” and it is the way the light appears when you look at it on a white page.  Bright white light is like daylight at noon, where warm white light is similar to what light looks like at sunrise and sunset.