If a color wheel is made withe the 3 primaries of red at 12 o’clock, blue at 4 o’clock, and yellow at 8 o’clock, then at 10 o’clock wold be the secondary color of orange (a mix of the primaries yellow and red) and at 2 o’clock would be violet (red + blue) and at 6 o’clock there would be green (yellow + blue). These 6 colors (3 primary and 3 secondary) each can then be seen to have a color opposite it on the wheel. For each primary there is a secondary opposite. For each secondary there is a primary opposite. Thus, red, (a primary) has green (a secondary) opposite it. Likewise violet and yellow, or blue and orange are opposites. We call each of these opposites ‘complementary’. They are very useful when mixing colors for neutralising, and painted beside each other, they ‘heighten’ the effect of the other. Green beside red makes the red seem redder for instance.