Text and important images must fall within the red boxes. Extending important elements to word these lines can cause problems during cutting, folding and assembly parts of images on text can end up being trimmed off or fall directly on fold.
Cut Fold:
This is approxmatily where your artwork will be trimmed. Keeping all text and important images will prevent thin unintended loss during cutting.
Bleeds:
This area is going to be completely trimmed away during the cutting process. Only solid colors, background images, or foreground images that intentionally run off the page should extend though this area. Having bleeds ensures that your artwork will not have a thin white foler around it.
Folds:
Be very careful when running any text or important image over folds. text, especially text under 9 pt can be hard to read if it is falling on fold.