The document discusses colour theory and colour psychology. It explains the colour wheel and primary, secondary, tertiary, analogous, complementary, split-complementary, triad, and tetrad colour schemes. It also discusses warm and cold colours, tints, shades, tones, colour value, colour harmony, and the psychological effects of different colours like red, orange, yellow, green and blue. Colour is an important design element that can be used to set moods and convey meanings through its psychological associations.