folios

Folio is a term used in books, manuscripts, and publishing with several related meanings. In its oldest sense, a folio is a single sheet of parchment or paper folded once to form two leaves, producing four pages. A book made from such sheets is described as a folio, and the term continues to be used to indicate large-format editions. In bibliographic practice, folio also denotes a size category: folio-sized books are typically larger than other formats such as quarto or octavo and were favored for display, reference, or scholarly works in earlier centuries.

In the history of printing, folios are associated with many early printed volumes and with ledgers and legal documents that required durable, wide pages. The notation f. or fol. for a single leaf and ff. for multiple leaves is common in catalogues and scholarly editions.

Notable examples include The First Folio of William Shakespeare, published in 1623, which collected Shakespeare’s plays and marks a milestone in English literature. In modern publishing, the term survives in occasional use to describe oversized, high-quality editions; it also influences bookbinding terminology and cataloging practices.

The word folio comes from Latin folium, meaning leaf. Its plural form is folios, though folia is occasionally seen in older or specialized contexts. In library catalogs, folio is used as a size designation and may appear as “folio” or its abbreviation “f.” or “ff.” in citations.