GIF: The Graphic Interchange Format is a compression format for images. Pictures and graphics you see on Web pages are usually in GIF format because the files are small and download quickly.
Gutter: The inside margin of a bound page or the line or fold at which facing pages meet.
GSM: Paper weight is measured in grams per square metre.
Greyscale: Shades of grey ranging from black to white; in printing, greyscale uses only a black halftone plate.
Grippers: Metal fingers which hold paper and carry it through printing impression to the delivery end of the press.
Gusset: Expandable portion of a pocketed folder or envelope.