Pagination is the process of dividing (content) into discrete pages, either electronic pages or printed pages. Today the latter are usually simply instances of the former that have been output to a printing device, such as a desktop printer or a modern printing press. For example, printed books and magazines are created first as electronic files (for example, PDF or QXD files) and then printed. Pagination encompasses rules and algorithms for deciding where page breaks will fall, which depends on semantic or cultural senses of which content belongs on the same page with related content and thus should not fall to another (e.g., widows and orphans). Pagination is sometimes a part of page layout, and other times is merely a process of arbitrary fragmentation. The difference is in the degree of intelligence that is required to produce an output that the users deem acceptable or desirable. Before the rise of information technology (IT), pagination was a manual process, and print output was its sole purpose. Every instance of a pagination decision was made by a human. Today, most instances are made by machines, although humans often override particular decisions (such as by inserting a hard page break). As years go by, software developers continually refine the programs to increase the quality of the machine-made decisions (make them "smarter") so that the need for manual overrides becomes increasingly rare.In reference to books made in the pre-IT era, in a strict sense of the word, pagination can mean the consecutive numbering to indicate the proper order of the pages, which was rarely found in documents pre-dating 1500, and only became common practice circa 1550, when it replaced foliation, which numbered only the front sides of folios.