In addition to specifying different artboards to crop artwork for output, you can also create and use multiple sets of crop marks within your artwork. Crop marks indicate where you want the printed paper to be cut. Crop marks are useful when you want to create marks around several objects on a page—for example, when printing a sheet of business cards. They are also helpful for aligning Illustrator artwork that you’ve exported to another application.
Crop marks differ from the artboard in the following ways:
Artboards specify the printable boundaries of artwork, whereas crop marks don’t affect the printed area at all.
You can activate only one artboard at a time, whereas you can create and display multiple crop marks.
The artboard is indicated by visible but non-printing marks, whereas crop marks are printed with registration black (so that they print to every separation plate, similar to printer’s marks).
Crop marks do not replace trim marks created with the Marks & Bleed options in the Print dialog box.
In Illustrator CS5, you can create editable trim/crop marks or create crop marks as live effects.
To use crop marks, do the following:
To delete an editable crop or trim marks, select the trim marks and press the Delete key.
To delete a crop marks effect, select Crop Marks in the Appearance panel, and click the Delete Selected Item icon .
Japanese-style crop marks have double lines, which visually define a default bleed value of 8.5 points (3 millimeters).