It refers to heating a standard blackbody, when the temperature rises to a certain degree, the color starts to change gradually from dark red light red orange white blue, when the color of a light source is the same as that of blackbody, we call the absolute temperature of blackbody at that time as the color temperature of the light source.
The light color varies with the color temperature of the light source:
Color temperature is below 3300K, light color is reddish to give warm feeling; there is stable atmosphere, warm feeling, commonly known as warm color temperature.
The color temperature is in the middle of 3000-6000k, and people have no particularly obvious visual psychological effect under this color tone, so it is called "neutral" color temperature
The color temperature is over 6000K, and the light color is blue, which gives people a cool feeling, commonly known as cold color temperature.