Page boxes refers to a number of rectangles used to contain and delineate content on the pages of PDF documents.
Over time PDF developed 5 different page boxes; each is used for specific tasks and often more then one is used in a PDF document. The requirements and conditions for the different page boxes are defined in the PDF specification itself and in supporting standards such as PDF/A or PDF/X. The following is a list of all five page boxes:
Each page box is defined by the coordinates of two of its points, traditionally the lower left and upper right corners. For more information on each of the page boxes, click on any of the links in the list above.