CMYK
The four process colors used in offset lithography printing. They are cyan, magenta, yellow and black (the key color). When these four colors are printed with halftone screens of various angles in this subtractive print method, they create oranges, reds, violets, and so on. The color gamut of CMYK is fairly limited, causing loss of color when a continuous tone photograph is reproduced using only 4 colors.
Indicia
Postal permit information printed on objects to be mailed and accepted by U.S. Postal Service in place of stamps.

Overrun
Number of pieces printed or paper made in excess of the quantity ordered.
Pantone Matching System (PMS)®
The registered trade name of a brand of color matching system commonly used in commercial printing. Pantone colors can be specified for ink, papers, plastics, and fabrics. Pantone chips are available for solid spot colors and for process ink mixes. Specifying Pantone colors is the only accurate and predictable way to know that the color in the imaging application is the color that will be printed (your monitor is NOT a predictable indication of printed colors).
Raster Image
Digital scanners and digital cameras produce raster images. A raster image can also be created new with a raster based application such as Photoshop® or Painter® or Canvas®. Raster images are pixel resolution dependent and can not be greatly increased in size without loosing picture quality. These are typically large files and are more demanding of RAM and processor speed. See also Vector Graphics.
Reverse
Type, graphic, or illustration reproduced by printing ink around its outline, thus allowing the underlying color or paper to show through and form the image. Also called knockout or liftout. The image “reverses out” of the ink color.
Tagged Image File Format (TIFF)
A common format for interchanging digital information, generally associated with greyscale or bitmap data.
Vector Graphics

Created from illustration programs such as Freehand® or Illustrator® , vector graphics are defined by points on the canvas and complex mathematical computations. Simple or complex shapes are created which can be overlapped, combined, aligned, etc. The shapes can be filled with color or gradients. Vector graphics have the advantage of creating small files and the artwork is always scalable to any size without loss of picture quality. Programs such as Illustrator also allow the placement of raster images on the canvas. In fact, the most recent versions of Photoshop and Illustrator really blur the line between the two programs.