A FOLIO is a term used to describe a folded manuscript sheet, which is a piece of paper that has been folded in half. It is often used to refer to a large sheet of paper that has been folded into four sections. This type of paper is commonly used for writing manuscripts, such as books, documents, and letters. It is also used for printing documents, such as newspapers and magazines. The term FOLIO is derived from the Latin word folium, which means leaf.