The very edges of the document are called the bleed area. To prevent an unwanted white border from showing at the edge of your document, be sure to extend any background colors or design elements all the way to the edge.
Trim lines are the finished size of the document. The document is cut close to the trim line, but because of the mechanical tolerances involved in printing, the actual cut can happen anywhere between the bleeds and the safe margin. This is why it is important to keep your text and important images within the safe margin.
When to create your document at the full bleed size If you are working in an illustration program (such as Adobe Illustrator or Corel Draw) or a photo editing program (Such as Adobe Photoshop or Corel Photo-Paint), we recommend that you create your document at the full bleed size. This will prevent any white edges from showing at the borders after the final product is trimmed.
When to create your document at the trim size If you are working in a layout program (such as QuarkXPress or Adobe InDesign) we recommend that you create your document at the trim size and include the specified amount of bleed for your product (.137”). When you export your document as a PDF for upload, make sure to include the bleed in your output settings so that the final upload PDF document is at the full bleed size for your product.
The safe margins are borders that are definitely inside the place where the cut will take place. Please remember to keep all important information, like names, addresses, phone numbers or logos within the safe margin (at least .137” from the edge) to ensure that they aren’t cut off when your document is trimmed.