What is bleed?
Bleed is a requirement specific to print jobs. Whenever you have a project where the final printed appearance contains ink that goes to the edge of the paper, bleed is required. The reason is that printing presses or digital presses cannot print to the edge of a piece of paper. The project must be printed on a larger piece of paper and then trimmed down to produce the final product.
Regardless of the application you use, one of the first things you need to determine is the finished size of the printed piece. Standard bleed in the printing industry is 1/8″ but it’s a good idea to check with your printer to be sure. When in doubt, ask!
When adding a bleed it is easy to get confused as to where the edge of the paper will be trimmed - to make sure all your important information and images are not trimmed off - use a safe zone. When setting up your margins - add a line for bleed, then a line for trim ( actual size of your document ) and then set up a line at least 1/4" inch AWAY from the trim line for your safe zone. This will help you keep any important info away from the edge and free from any chance of getting cut off when your project is trimmed to final size.
Exporting your file / Creating a .pdf
If your program allows - when you create your press ready .pdf - save the document to include crop marks, with an OFFSET of .125 - do NOT use "printers marks" Crop marks only will be sufficient.