Page numbering is the process of applying a sequence of numbers to the pages of a book or other document. The number itself, which may appear in various places on the page, can be referred to as a page number or as a folio. Like other numbering schemes such as chapter numbering, page numbers allow the citation of a particular page of the numbered document and facilitates to the reader to find specific parts of the document and to know the size of the complete text.
Page number in a book
The term "folio" has three interconnected but distinct meanings in the world of books and printing: first, it is a term for a common method of arranging sheets of paper into book form, folding the sheet only once, and a term for a book made in this way; second, it is a general term for a sheet, leaf or page in (especially) manuscripts and old books; and third, it is an approximate term for the size of a book, and for a book of this size.
The title-page of the Shakespeare First Folio, 1623
Single folio from a large Qur'an, North Africa, 8th c. (Khalili Collection)
Copy of the Gutenberg Bible, printed in folio format