Color is simply light of different wavelengths and frequencies and light is just one form of energy that we can actually see that is made up from photons.
We are all surrounded by electromagnetic waves of energy of which colour is just a small part.
Each colour has its own properties and unique wavelength and frequency.
more about... Colour properties
The visible spectrum of colour as we see it, consists of seven main colours:
The retinas in our eyes though have three types of colour receptors in the form of cones. We can actually only detect three of these visible colours - red - blue and green. These colours are called additive primaries. It is these three colours that are mixed in our brain to create all of the other colours we see... how clever we are!
The wavelength and frequency of light we see, also influences the colour we see. The seven colours of the spectrum all have varying wavelengths and frequencies. Red is at the lower end of the spectrum and has a higher wavelength but lower frequency to that of Violet at the top end of the spectrum which has a lower wavelength and higher frequency.