Crop marks are the indicators of where the final trimming of the printed piece will take place. They also serve as guides to align the printed image on exact size sheets. They are very important if you are at all concerned about where the image appears on the paper.

Without them, there is no way to tell where to position the image on the print sheet, nor is there a way to know where to trim to.

In no place do they touch the finished area, so that they can be trimmed off. Crop marks should also be used to indicate folds, score lines, perforations, etc. Again, these should be outside of the trim size of the final piece.

Register marks are used to align multiple colours. They need to occur in exactly the same position on all original separations on multi-colour work. If possible, they should be placed outside the final trim area, but inside the press sheet area. “Tight register” refers to how tightly the various colours align to each other.