To see colour, we have to have light. When light shines on an object some colours bounce off and others are absorbed by it. Our eyes only see the colours that are bounced off or reflected.
The sun’s rays contain all of the colours of the rainbow mixed together — this mixture is known as white light. When white light hits a red object, lets use an apple as an example, it appears red to us because it absorbs all other colours except red, which are bounced off. Our eyes receive this reflected light and send the message to the brain, which interprets it as red.
We all perceive light and colour differently. What you see as red is different from what I see as red, although we will both call it red.
In colour theory hue refers to a pure colour — one without tint or shade.
A hue is generally defined as a source colour, the purest and brightest family of twelve basic colours located on the colour wheel. Every conceivable colour has one of these hues as its root.
Burgundy – the root colour or hue is red
Brown – the root colour or hue is orange
Navy – the root colour or hue is blue
There is also something known as relative temperature. When comparing different colours, one can be warmer or cooler than another. For example, when we compare the violet in the centre of the image below with the two variations on either side, we can see how the one to the left is warmer (closer to red) than the one in the centre or to the righthand side. Conversely, you can also see how the one on the right of the centre square is cooler (closer to blue) than the squares on the left.
In the case, where we have two variations of the same hue, one square would be described as cooler if it has more blue, violet or green undertones than another, whereas we would describe it as warmer if it has more red, orange or yellow undertones.