Folio

What does folio mean in the world of book printing?

In book printing, a folio refers to the page number printed on each page of the book, it usually located at the top or bottom margin.

Folio FAQ

Are folios printed on every page?
Not for every book, sometimes the designers might not apply folios on chapter title pages, blank pages, or full-spread images for aesthetics purposes.

What's the difference between folio and drop folio?
A folio is the general term for a page number. A drop folio specifically refers to a page number placed at the bottom of the page.