Colour is one of the strangest things in the world. It looks as though there ought to be many colours in the world, each different. But there are not. There is no such thing as white light, for example. It turns out that white light is a 'colour' produced when lights of many other colours mix together.

We can show you that in the video below.

The colour we see when white light shines onto to something is a matter of what kinds of light that object soaks up, and what parts of the white light it bounces back into our eyes. So, for example, a red book will have soaked up (absorbed) all of the other colours that make up white light (red, blue and green), so that only red light is bounced back. It is the same for all colours.

This also means that we can put filters in front of light to block out some colours and not others.