Subtractive Colour VS. Additive Colour.

Subtractive - the more colours you layer on top of each other the less light is reflected - colours are subtracted so it becomes darker until you end up with black. 

Subtractive colours is what happens when you mix paint, print a picture, or highlight a word on a page.

Additive Colour - The exact reverse of Subtractive colour, the more colours you mix the lighter it becomes.

Additive colour occurs with televisions, computer monitors and all screen based images. 

Additive colours model involves light emitted directly from a source.