What is bleed?
On any print project, if the print needs to go right to the edge of the page, we will require the artwork to have a bleed. This is an extension of the artwork past the final size of the product.
Why is it needed?
When printing jobs, we will print more than one copy on a larger sheet of paper and trim this down after print. With all printing presses, there is a small print shift from one sheet to the next. This shift may be less than one millimeter, however when guillotining a pile of printed sheets, this sheet to sheet shift would mean some sheets would have small white edges visable. To avoid this, we add a 3mm extra print which is trimmed away.
How should my artwork look?
Below is an image showing how your artwork should look. Most packages have options to add printers bleed and crop marks when creating your pdf. If in doubt, ask!