Subtractive and Additive colour.
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 colour is what happens when you mix paint, print a picture, or highlight a word on a page.
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.
Colour systems.
Technical, essential knowledge for control of your work.
Terminology
CMYK (cyan/magenta/yellow/key black – 4 col process)
This is used in the most common printed process called litho or offset litho
RGB (red/green/blue – screen based)
Greyscale (Black and white continuous tone, any shade of grey such as a black and white photograph)
Duotone (when a continuous tone image is printed in 2 or more spot colours – this term is also generally used when describing tri and quadtones.
Spot colour (one or more specially mixed colours as opposed as a result of a CMYK or RGB mix)
Mono (like greyscale but with a coloured ink, ie:one colour only plus the colour of the material it’s printed on)