Visible light and colour makes up just a very small part of the Electromagnetic Spectrum.
To make it a little easier to understand about light and waves of energy, the electro magnetic spectrum provides an illustrated method of showing the types of electromagnetic radiation in terms of wavelenghth and frequncy, and how small a part visible light actually is in the whole spectrum.
Visible light energy is made up of many frequencies and wavelengths and falls between Infrared and Ultra violet.
The rest of the Electromagnetic spectrum is made up from many other waves and energy including radio Waves, microwaves, infrared waves, ultraviolet waves X-Rays and gamma rays.
Electromagnetic radiation itself can be described as being a stream of photons (massless particles) moving at the speed of light (186,000 miles per second) and traveling in a wave-like pattern. All electromagnetic radiation, consists of these photons each having its own energy.
Different forms of electromagnetic radiation have different amounts of energy. Radio waves for example have a less energy than microwaves. The reason for this is because the photons of radio waves, have a lower frequency or cycles per second - hertz ( htz for short) and therefore less energy.
Like all electromagnetic radiation, light travels in waves. These waves are vibrations of electric and magnetic fields that pass through space.
In physics, the visible spectrum has three primary colours - Red, Green and Blue. Chemically, colour is derived from pigments and compounds and the three primary colours here are Red, Yellow and Blue. Any of these two colours will give a third colour - a secondary colour.
The sensory aspect of colour is visual and deals with the physiology and psychology. So here we see the two above systems in the perception of sight and there are then two combinations of three primary colours, i.e. Red, Yellow and Blue and Red, Blue and Green. All other colours are derived from these.
The diagram below, shows what a small part of the whole electromagnetic spectrum visible light actually forms.