Bleed refers to a background color, graphic, or image that prints to the edge of the finished paper.
Printing presses can’t apply ink all the way to the paper’s edge. So an extra .125″ (3mm) margin is added anywhere a design needs to print to the edge. This lets the background color, graphic, or image extend or “bleed” past the paper’s final trim edge. All bleed areas are then trimmed off the printed sheet at some point in the finishing phase. For example, a letterhead sheet that uses bleed in its design will be 8.75″ x 11.25″ and is then cut to its final size of 8.5″ x 11″.
In comparison, a piece with no bleed keeps all the printed elements a minimum of .125″ away from the edge of the paper on all four sides. Nothing is printed to the finished edge of the paper, as shown in the illustration.