bookbinding Bookbinding is the process of physically assembling a book of codex format from an ordered stack of ''signatures'', sheets of paper folded together into sections that are bound, along one edge, with a thick needle and strong thread. Cheaper, b ...

, a section, gathering, or signature is a group of sheets folded in half, to be worked into the binding as a unit. Grecquage

The section is the basic building block of codex bindings. In Western bookbinding, sections are sewn through their folds, with the sewing thread securing each section to the one bound before it. The gatherings can be seen by looking at the top or bottom sides of the book, though cheaper modern books are perfect bound with no gatherings, each sheet glued directly to the binding. The gatherings are sewn together at the spine, done in such a way that two or more stretches of thread are visible along each gathering's innermost fold. In medieval manuscripts, a gathering, or quire, was most often formed of four folded sheets of

vellum Vellum is prepared animal skin or membrane, typically used as writing material. Parchment is another term for this material, from which vellum is sometimes distinguished, when it is made from calfskin, as opposed to that made from other anima ...

parchment Parchment is a writing material made from specially prepared untanned skins of animals—primarily sheep, calves, and goats. It has been used as a writing medium for over two millennia. Vellum is a finer quality parchment made from the skins of ...

, i.e. 8 leaves, 16 sides. The term ''quaternion'' (or sometimes ''quaternum'') designates such a unit. A gathering made of a single folded sheet (i.e. two leaves, four sides) is a ''bifolium'' (plural ''bifolia''); a gathering of two sheets (i.e. four leaves, eight sides) is a ''binion''; and one of five sheets (10 leaves, 20 sides) is a ''quinion''. This last meaning is preserved in the modern Italian meaning of ''quire'': ''quinterno di carta''. When bookbinders started using paper, it became possible to easily stitch five to seven sheets at a time, and the number of sheets per gathering started to vary more.

See also