A printer ribbon is a spool of alternating colored dyes housed in a cartridge. Used in dye sublimation printers, the four CMYK colors are used for each print. A CMYKO ribbon refers to CMYK plus the clear overlay used at the end. For ID card printers that print on both sides of the card, a CMYKOK ribbon is used, which prints black on the second side (last K in CMYKOK). See CMYK
and dye sublimation printer
Each print has its own set of CMYK colors on the ribbon. Unlike inkjet cartridges, which run out at different times depending on how much ink is used, printer ribbons have a fixed number of prints regardless of which colors dominate in the image.