Trim, bleed, and safe area are three zones that keep your design intact through cutting and binding. Get them wrong and you get white edges or cropped text.
Trim size
Trim size is the final size of the piece after cutting. Your document should be set to trim size (or to trim plus bleed, depending on the app).
Bleed
Bleed is the extra area beyond trim where background or full-bleed art extends. We need it because cutters are not perfectly exact; without bleed, you can get a thin white line at the edge.
Typical bleed
For many small-format pieces, 1/8 inch (0.125 inch) bleed is a common starting point. Use the template or confirmed specification for the job; banners, bound pieces and specialty cuts can need different allowances.
Safe area
Keep important text and logos inside the finished edge, with extra room around folds, binding or hardware. A 1/8 inch margin is a common starting point for simple small-format work, not a guarantee for every product. Follow the agreed safe-area specification.
Common mistake
Running text or key art right to the trim with no bleed or safe margin. One small shift at trim and the edge looks broken or text is cut off.