Glossary
Print file
A print file is the production-ready artwork sent to the printer: correct dimensions, correct resolution, correct colour mode, and positioned for the product's print area. It is not the same file you would use for a listing image.
Most rejected or disappointing orders trace back to the print file rather than the printer. Artwork exported at screen resolution looks fine on a listing and prints soft; artwork without bleed can show a white edge after trimming.
The safe habit is to build artwork at the print size from the start rather than scaling a small file up. Enlarging cannot add detail that was never captured.