Bleed is an extension to the edges of your pages, to sustain content placed at the edge of a page once the document is trimmed.
When full bleed is supplied, the excess 3mm (extension which goes beyond the page's edges by 3mm) will then be trimmed off, ensuring your artwork is printed to the edge of the page.
We recommend supplying bleed to documents which contains background colours or artwork which goes to the very edge of the page.
If bleed is not included, your artwork may be printed with white borders.