Adding bleeds to print ready files is an industry standard. If you are designing your own files, this is a must know.
What is bleed? Bleed is the image or color that extends beyond the actual document size. It should extend by 1/8". Under certain circumstances, it may extend by 1/16" which is the absolute minimum.
“YOUR FILE NEEDS BLEEDS UNLESS IT HAS A WHITE BORDER.”
Why have bleed? Bleeds allow you to run image or color to the edge of a page. Printing and finishing process may have small machine or material variations that can end up leaving a hairline white edge where there should be no white edge at all. Extending images 1/8" beyond the final trim size guarantees that images truly will go all the way to the edge of the printed paper, after the final finishing process.
How to add bleed? Create your document to final finished size. Add 1/8" bleed to the outside edges of your document. If your document is 8.5x11", set your document size to 8.5x11". Add the .25" bleed. Your image can now extend the document size. Once complete, export your document as a PDF. The final size of the file including the bleed will then be 8.75x11.25".