There are two key colour modes to be aware of in digital design; RGB & CMYK.
RGB: Red + Green + Blue
Use for: Screen (web, email, presentation, CD ROM, moving image).
Some high end photographic printers.
Pros: Produce a wide range of colours including very luminous hues.
Cons: Can’t send to offset print.
Difficult to colour manage.
RGB are referred to as additive colours as white is created by adding all these hues of light together.
CMYK: Cyan + Magenta + Yellow + Black (key)
Use for: Print (offset, laser, inkjet, digital).
Pros: This colour format is the most frequently used in variable colour printing. Print runs are typically cheap as machines are set and ready to go.
Cons: Difficult to colour manage.
Difficult to reproduce RGB colours.
Cannot produce metallic or fluorescent effects.
Larger file size.
Can’t display on screen.
CMYK are also referred to as subtractive colours as white is created by subtracting all coloured inks from the page.