The bleed is the area at the edge of a document which gives us space to allow a cleaner finish for trimming. Bleed is generally required to be 5mm on all edges for jobs with any images, backgrounds or colours that extend to the edge of the page. For example, an A5 book's dimensions are 210mm x 148mm; with 5mm bleed it will be 220mm x 158mm. The extra 5mm bleed will be cut off, so any important text or images should not appear in or near this area.