USAGE (IMPORTANCE) OF COLOUR IN GRAPHIC DESIGN

Colour is a perception of light by human brain. In simple words when a ray of light strikes an object, the object absorbs a colour and reflects remaining colours. Human brain identifies the missing colour and perceives the colour of the object as that of the missing colour. This phenomenon is widely known as perception of colour.
"Colour is life, for a world without colour seems dead. As a flame produces light, light produces colour. As intonation lends colour to the spoken word, colour lends spiritually realized sound to form." - Johannes Itten.