Color, in terms of pigment, is every shade and hue found in a brand new box of crayons (and any combination you could make from them). To put it in scientific terms, however, color is simply the range of visible light that humans can see. Different colors, such as red and orange, and other invisible spectrums such as infrared light, move around in waves of electromagnetic energy. The human eye is capable of seeing only light with wavelengths between 380 and 750 nanometers. For example, the visible spectrum begins with the wavelengths that we call violet, between 380 and 450 nm, then moves on to blue, green, yellow, and orange, and ends with what we call red, between 590 and 750 nm. When you look at someone’s red shirt, for instance, that shirt will be absorbing or scattering wavelengths of light lower than 590 nm, so those waves will not reach your eyes. But a red shirt will be reflecting some wavelength between 590 and 750 nm, which your eyes process as red.
The trouble in this scientific approach is that some colors considered important in the crayon box are notoriously missing. Black and white, as well as colors like pink, don’t seem to have a place in a visible spectrum of light that goes only from violet to red. So does this mean that black and white aren’t real colors?
It depends on how you want to define color. If color is solely the way physics describes it, the visible spectrum of light waves, then black and white are outcasts and don’t count as true, physical colors. Colors like white and pink are not present in the spectrum because they are the result of our eyes’ mixing wavelengths of light. White is what we see when all wavelengths of light are reflected off an object, while pink is a mix of the red and violet wavelengths. Black, on the other hand, is what our eyes see in a space that reflects very little light at all. That’s why, if you enter a room with the lights turned off, everything is dark and black. If you include in the definition of color, however, all of the ways in which human eyes process light and the lack of it, then black and white, as well as pink, earn their places in the crayon box.