A sensation of light in the eyes induced by certain frequencies, each colour of the rainbow as we know it, having a different frequency.  Colour is applied to textiles by dyeing and printing.  The basic, so called primary colours, are red, blue and yellow.  Secondary colours are made up of a mixture of two of each of the primary colours: red + blue = purple; blue + yellow = green; yellow and red = orange. The word hue normally means red colour, blue colour and yellow colour. The word shade is a colour which has been made darker with black. A tint is a colour which has been lightened with white. The word tone, often mis-used, means lightness, darkness or brilliance of colour.