The color temperature is measured by the absolute temperature K (kevin), which is to heat a standard black body (such as iron), when the temperature rises to a certain level, the color starts from red -> light red -> orange -> white -> blue White -> blue, gradually changing. Using this characteristic of light color change, when the light color of a light source is the same as the light color of a black body at a certain temperature, we call the absolute warmth of the black body at that time as the color temperature of the light source. When the color temperature is below 3000K, the light color starts to become reddish, giving people a warm feeling. The color temperature exceeds 5000K, and the color is biased towards blue, giving people a cool feeling.