Before looking at how to use colour in your interior design project here is a little background information (some of the colours on this page may not appear as 'pure' as in real life are only meant as a guide.

The Colour Wheel

Sir Isaac Newton drew the first colour wheel in the 17th century and thus should, in diagrammatical format, the interrelationship between colours, albeit at a very simple level

Primary Colours – colours that are not mixed from others

Secondary Colours - mixed from primary colours

Tertiary Colours - mixed from one primary and one secondary colour

Colour is created by the way the eye perceives different wavelengths of light as it is reflected off various surfaces.  There are different dimensions to colour: 

The Hue – used to distinguish one colour family from another.   

The Chroma – sometimes called the saturation of colour and being the intensity/purity of that colour.

The Value or Tone – used to distinguish a light colour from a dark one. 

The Tint – this is a lighter version of a colour created by adding white to that colour. 

The Shade – this is created by mixing either black or the colour’s compliment with the colour.

Colours also have a ‘temperature’ some are warm, others cool and this is the result of the reflected light wavelength either coming from the infrared (warm) side or the ultraviolet (cool) side of the visible spectrum. 
As a result colours such as red-orange are on the warm side, blue-green on the cool.

 When looking to design an interior it is important that thought is given to how to use colour and there are a number of options available:

Monochromatic Colours

The very name of this set of colours suggests monotony - one colour only in the scheme!  To this one colour we can add white, grey or black in differing quantities and providing you only use a little of another colour as a hue you're not cheating.  This type of scheme can look very sophisticated and works best if used with a lot of texture.  An example would be, using Violet as an example:

Complimentary Colours 

These are colours that appear exactly opposite one another on the colour wheel such as red and green.

Analogous Colours

 These are any two or three colours that are side by side on the colour wheel such as red, red/Violet and Violet – although one of the three colours is usually the predominant one in the design.  This is a very harmonious use of colour.

Split Complimentary

This is where one colour is chosen from one side of the wheel and two from the other side

Triad

Each of the three colours used in this scheme are to be found equidistant from each other around the colour wheel.   This is a rather tricky collection of colours to use and should be approached with caution.

Double Complementary

As the name suggests this is where two pairs of complimentary colours from each side of the colour wheel are chosen.

A useful exercise to complete to understand how colours interact is to complete colour exercises as shown below that Kandinsky encouraged his pupils at the Bauhaus to complete.