Bleed
Artwork extended past the final trim line so that normal cutting variance never leaves a white sliver at the edge. Commercial printing typically asks for 1/8 inch (3 mm) on every side; large-format work often wants more.
In practice A background that stops exactly at the trim line will show a white hairline on some pieces in the run. Extending it costs nothing at design time and cannot be fixed after printing.
Business Cards & Print Collateral