Two identical lamps can create completely different interiors—all it takes is a 2700 K bulb in one and a 6000 K bulb in the other. Color temperature is, alongside power, the most important parameter of a light source, yet it is also the one most often overlooked when making a purchase. We explain the difference between warm and cool light tones, what color temperature to choose for your living room, kitchen, and bedroom, and why 6000 K is almost never a good idea for your home.