Further information about colour theory

Colour theory is complex and is based on colour models and colour spaces.

Defining colours

Colours are defined in many ways, three of the more common ways are:

  • RGB (red, green, blue) – which describes the type of light emitted to produce a colour
  • HSL (hue, saturation, luminance) – commonly used by artists
  • CMYK (cyan, magenta, yellow, black) – used in printing to describe the inks required to produce a given colour

Example of how a colour can be defined

An example of a shade of turquoise.

This colour can be defined in the following ways:

RGB(35, 165, 142), HTML traditionally uses hexadecimal conversions of the RGB value to define colour. For example #23A58E

HSL(169.38°, 78.79%, 64.71%)

CMYK(77.75%, 11.45%, 54.28%, 0.34%)

You can use at least one of these methods to define colour in most software packages.

We are constantly improving based on research and best practice. Any significant changes to our guidance are available on the Updates page.