Glossary of printing terms (artwork and origination):

Bleed
The area of an image outside the crop marks, cropped off to allow the resulting image to print to the edge of the page.

Crop mark
The mark indicating the position in which the sheet is to be trimmed.

The Em
A measurement consisting of 12 points or 4.5mm.

Justification
Type aligned on both sides of the text, achieved by the spacing of letters and words.

Kerning
The fine tuning of spacing between letters.

Leading
The spacing, in points, between lines of text.

Point
A printing measurement. 72 points to an inch.

Point size
The size of type measured from the baseline of type on one line to the baseline of the text on the next.

Range left/right
Body copy aligned to the left or the right with the opposite side ragged.