Colour wheels show us how colours are related. They remind artists how to mix and think about colours.
The primary colours are:
Primary colours cannot be made from other colours. Artists create all the other colours of the rainbow by mixing together the primary colours.
The secondary colours are:
Secondary colours are made by mixing two primary colours. Each secondary colour is made from the two primary colours closest to it on the colour wheel.
Just by mixing these colours, you can get all the colours of the rainbow: