What is quire definition?

A quire is a unit of paper or parchment typically containing between four and eight sheets, folded in half to form two leaves. It is used to describe the number of sheets in a manuscript or bookbinding, and can also refer to a group of these sheets bound together. The sheets in a quire were traditionally cut from the same large sheet of paper or parchment, resulting in a consistent size and thickness throughout the book. Quiring was a common practice in the Middle Ages and continued to be used in early printed books.