There has long been a debate about whether black and white are technically considered colours. In practical terms for art and design, black is generally considered to be a color since you can create it by combining other pigments on paper. Black, white and grey are often referred to as achromatic colours since they have no hue.
However, in the technical sense, black and white are shades rather than colours. They augment colors but do not function like colours themselves.White is the result of all wavelengths of light reflected off an object, while black results from the absence or complete absorption of visible light.