# Colour theory for the web

## Scott Kellum introduces some basic practice to help make use of relative colour and make web designs more flexible.

There are lots of colours available to us, and for the most part, we describe colour in a way that makes it difficult to see the relationships between different colours. Names like red, green, blue, yellow, purple and maroon are great for conversations about colour but provide little insight into the structure of that colour. From the moment we can talk, colour is processed by the language part of our brains and its meaning is tied to the names we give colours.

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Dimension, on the other hand, is processed differently by our brains. One foot and three feet aren't called different names. Instead, we measure dimension in a way that's proportional to a constant and well-known increment like inches or centimetres. These ideas of measurement come naturally to us and, while colour can be measured and described in a similar way, it's often very difficult for us to understand and manipulate colour as a measurement of its parts.

It wasn't until Sir Isaac Newton did a series of experiments with prisms in the 1600s before we really started to understand that light was made up of different colours that could be measured independently of one another. Colour wheels were soon adopted by artists so they could better understand and mix colours.

See Scott's demo of everything he discusses in this tutorial here

While most artists use red, yellow and blue as primary colours, and most colour theory classes refer to these as the primary colours, science has evolved since the days of Isaac Newton and so has our understanding of how we see colour. Just about everyone's eyes contain various light receptors. Receptors called rods detect darks and lights, and cones detect three primary colours: red, green and blue.

These three primary colours probably sound familiar to those of us who work on the web because this is how we write colour. Monitors have red, green and blue parts to every pixel. Each colour has 256 variations in brightness resulting in a total of 16,777,216 different colour possibilities. We can describe colour with the RGB colour function rgb(255,115,0) or hex values #FF7300, both of which describe the same colour in a slightly different way.