There are different terms you may encounter when colour printing. When saying 1C printing, it refers to one color being used when printing.
4C printing refers to CMYK printing; this is the most common colour print combination used in digital print shops today.

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Certain print shops will set out different colour combinations for different sides of a print. For example, the prompt “letter sizes pages 4c x 1c” means 4 colors on one side of letter-sized sheets and 1 color on the other side.

In addition, special photo-printing may require certain specifications.6C printing can be either hexachrome or dark/light. Hexachrome means the 4 colors from cmyk plus orange and green are used; using this results in more vibrant pictures. Dark/light specifications indicate that a CMYK colour combination plus lighter shades of cyan and magenta are used- using this combination results in more photorealistic images. 

8C is 6C Dark/Light plus diluted yellow and black; this results in more photorealistic, smoother, less grainy images.

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