Color is a particular spectrum contained in a perfect light (white). The identity of a color is determined by the wavelength of the light. For example the blue color has a wavelength of 460 nanometers.
The color wavelengths that can still be captured by the human eye range from 380-780 nanometers.
In optical equipment, color can also mean brain interpretation of the three primary colors of light: red, green, blue combined in certain compositions. For example mixing 100% red, 0% green, and 100% blue will produce a magenta color interpretation.