Colour models help to relate and coordinated colours with one another when working with different light sources, media such as paints or inks, objects and materials.
Colour models clarify the ways in which coloured lights, transparent inks and opaque paints (etc.) all produce different results when mixed.
Colours models help us manage the fact that colours behave and appear differently:
When emitted by different types of light sources.
Depending upon the type of media – inks, dyes, pigments.
When seen or used in different situations (indoors, in sunlight, in low light, on a digital display etc.)
When applied to, mixed with, or projected onto different materials.
When used for different purposes (fabrics, electrical wiring and components, print media, movies etc.)