Spot colour refers to a colour that is mixed as a special ink - for example, a Pantone® colour - rather than being made up of tints of process colour (CMYK) inks.

For example, if you were printing something entirely in green, with the spot colour approach you would mix up a green ink, and use one printing plate with that special ink; whereas if you were printing in CMYK you would be using four plates - for the cyan, magenta, yellow and black inks - and the green would be made up of a combination of those inks (eg 100% cyan, 0% magenta, 80% yellow, 10% black).

Spot colour printing tends to be more cost-effective for jobs with 1 or 2 colours.