The ABC of Photography – Colour temperature
All light sources have a characteristic colour temperature:
Artificial (tungsten-filament) lights are warmer (more orange) than daylight, which is warm near dawn, turns cooler (bluer) during the day, then warms again at nightfall.
Our eyes adjust for colour temperature much of the time without our realizing it, so that colours look pretty consistent.
Digital cameras can make electronic adjustments using a white balance system to neutralize colours. When they get it wrong (or you use the wrong white balance setting on your camera), a colour cast results.
Sources: Pixabay, Wikipedia, Susan Wingfield Lamar High School