A color is a sensory impression mediated by the eye and brain, which is caused by light, more precisely by the perception of electromagnetic radiation of the wavelength between 380 and 780 nanometers. It is the sensory impression by which two contiguous, featureless parts of the visual field can be distinguished in single-eyed observation with the unblinking eye alone.

In everyday language, colorants (color-providing substances) are also referred to as color, i.e. material means by which the color of objects can be changed.

Color perception is a subjective sensation, which is determined not only by the type of incident light radiation, but also by the condition of the eyes, sensitivity of the receptors and the perceptual apparatus. Other optical perception phenomena, such as structure (light-shadow effects), gloss or roughness, as well as psychological effects, such as retuning or adaptation, are to be distinguished from the concept of color.