Ink that goes all the way to the edge of the paper is called “bleed”. This means that the printer is going to request bleed to be included on all four sides of your document.
The most common way printers achieve this result is to print on a larger sheet of paper than needed and trim it down to size. If your artwork is the exact size of the finished piece, it’s possible that a slight shift while trimming will result in a white edge on the final piece. Bleed is artwork that extends past the trim line of the document.