Most products which are printed need what is known as a “bleed area”.
The size of the area varies according to the product but for most paper items it is 3mm.
See the images below to get an idea of how this works.
After your product is printed it is then trimmed to the alignment marks shown at each corner of the rectangles above. The red line around the green area represents the finished size.
When the item is trimmed it is possible that the cut is not perfectly aligned and unsightly white fringes are visible. In order to avoid this the background layer needs to extend beyond the actual size beyond the trim marks.
If you look closely at the zoomed image of rectangle “B” on the right you can see that the trim marks are aligned with the red cut line but are safely inside the green bleed area.
The yellow line, incidentally, represents the “safe” area. All small images and text are more easily understood by the reader if kept inside this area, normally 5mm from the trimmed edge.
Some signage products such as roll-up stands and banners have different bleeds and considerations but we have templates for all items and can advise on the requirements for each as needed.