TRIM
This the actual page size. We hope that each page will be cut (trimmed) along these lines. But we must allow some margin for error
BLEED
This is the margin for error in case the page is cut a millimetre or 2 in the wrong direction. This prevents any white paper showing through. Allow 3mm extra in all 4 directions so an extra 6mm height & width
TYPE This is the area we recommend that important images or text should stay within to ensure it isn’t lost when the page is trimmed