Colour Theory

Book Ref: 'Contemporary Color: Theory and Use', Steven Bleicher, Delmar Cengage Learning; 2nd Revised edition edition (11 April 2011)
Book Ref: 'Color Theory' José María Parramón, Watson-Guptill Publications, 1989 

What is Colour Theory Context?
Within the visual arts Colour Theory is the process by which we mix spectrums of light and tone to create what we see as colour combinations. The definitions of these colours are based upon a set of three spectrums known as Colour Wheels; these consist of primary colours, secondary colours and tertiary colours. Although colour theory was present within the artistic notebooks of Da Vinci, its actual creation as a theory concept was not established until the 18th century by Sir Isaac Newton in 1704 within his work on visionary science. The way that we as human beings see colour is an experience based upon sensory responses to light rather than a physical creation, this is why some people interpret the colour of objects and materials differently from the next. The most important concept to understand within colour theory is the difference between the colours we see through light mixtures, known as additive colour, and that of pigment mixtures, called subtractive colour. How our eyes absorb colour has a great impact on the final tones that we see through our Iris. 
The visual effects of colours can be described through the following three terms:
1. Saturation (the intensity of a colour or how dull it is)

Newtons Spectrum of Colour
http://www.colourlovers.com/blog/2008/05/08/
history-of-the-color-wheel

2. Lightness (whether a colour is light or dark in tone or black and white)
3. Hue (these are the overall tones of a colour, these can differ from: red, orange, yellow, green, blue or purple.
On the whole it is scientifically believed that the whole spectrum of colour visible to the human eye can be created from the mixing together of the three primary colours yellow, blue and red.

Goethe's Colour Wheel
http://www.dw.de/image/0,,5918676_4,00.jpg

This idea of colour observation was summarised into two founding documents of colour theory: 'The Theory of Colours' by German poet and government minister Johann Wolfgang von Goethe in 1810, and 'The Law of Simultaneous Colour Contrast' by French chemist Michel Eugene Chevreul.

Chevreul Colour Wheel
http://www.holidayclubrecordings.co.uk/post/
michel-eugene-chevreul-science-colour

What is a Colour Wheel?
The first colour wheel was created by Sir Isaac Newton in 1706 a portrayed the spectrum of colour from red through to violet, that he had established within his research of how light creates colour when manipulated through light and dark tones. Newton took his theory of the spectrum created by the passage of light through a prism and formed a segmented circle whereby each colour was organised into a segment according to their position in the spectrum. The two circles opposite are examples from the Traité de la peinture en mignature 1708 which depicts the connection between Newtons theory and the colour pigments used within art. 
However it was Goethe's theory in 1810 of the systematic study of the physiological effects of colour that proved the effects that opposed colours have on the eye, this is what know today as complementary colour theory. 
Michel Eugene Chevreul furthered additional research into the colour wheel developing a theory of how optical illusions are created when two colours are placed close beside one another depending on whether the second colour is lighter or darker in hue. However most famously Chevreul developed the art of how colours are optically combined by the eye to suggest a third colour; for example when red and yellow are merged to create orange.

Analogous Colours
Groups of colours that are adjacent in the colour wheel. One colour often being a dominant primary or secondary colour and two on either side complementing tertiary colours.
Monochromatic Colours
This means that here is one selected hue whereby the colour are made up of the selection of tints, tones and shades all located within the spectrum of that one hue.
Complementary Colours
These colours are commonly a pair that face opposite from each other on the colour wheel, for example purple and yellow. When combined they cancel one another out to create black but when placed side by side are harmonising to the eye.
Achromatic Colours 
Achromatic colours are what is produced when two complementary colours cancel one another out. Often this is left with a greyscale spectrum from black to white.