Stands for 4 colors on the front of a page and 1 color on the back. When 4 is used, mostly it refers to CMYK colors or “full color.” The 1 means it will be a spot color, such as a Pantone color. The numbers can be of any number, such as 6/3, meaning 6 different spot colors on the front and 3 on the back, but those mentioned here are the most common for most print projects. See also 4/4, 4/K.: A print job with four color printing on the front side and one color (usually black) on the back side  

Stands for 4 colors (”full color”) on the front and back of a page.: A print job with four color printing on both sides of the paper.

Stands for 4 colors (”full color”) on the front and blacK ink on the back.