Though historically the primary purpose of colour was surely to enable us to survive more easily in the world, today colour is used for a multitude of purposes. Colour is used to communicate, to advertise, to attract, to amuse, to frighten, to please, and to evoke. Colour now plays an immense role in our lives. It has been said, for example, that when shopping, on average people make a preliminary decision about a product in only 90 seconds and around 60-90 percent of their judgment is just based on colour. One of the reasons that colour can have such a prominent effect is because colour evokes within us emotions and conveys messages. The area of research that studies this is generally known as colour semiotics. The effect of colour on our mental state is complex and not always easy to predict. Certainly there is variation in the effect from person to person and there are undoubtedly differences in the effects as we move through times or if we compare one culture to another. One reason for this is that the reasons for the psychological effect of colour are varied. So, for example, it is likely that some effects of colour have been with us for hundreds of thousands of years. The colour red is associated with danger and the colour black is often associated with fear and evil. It’s possible that these colours trigger deep-seated emotional responses to the colour of blood and to the darkness of the unknown night, for example. However, interacting with these primordial colour associations is the effect of culture and society. For example, in many societies we associate blue with boys and pink with girls. This would seem be a product of our culture and something that is not fixed in stone but which could be changed in the future with changing trends and fashions. A further example would be the association of purple, particularly in western civilizations, with royalty and richness. In the 4th Century BC the purple dyestuff known as Tyrian Purple (or royal purple) was as expensive as silver. It is not surprising that the Christian church, keen to demonstrate its wealth and power, would choose to incorporate purple into its robes and other paraphernalia. It is therefore easy to see that the meanings and associations we have for colour are not wholly consistent across the globe. The semiotic content of colour coupled with its emotional impact makes colour an extremely powerful tool for advertisers and an important factor for the consideration of design.