In the hand press period (up to about 1820) books were manufactured by printing text on both sides of a full sheet of paper and then folding the paper one or more times into a group of leaves or gathering. The binder would sew the gatherings (sometimes also called signatures) through their inner hinges and attached to cords in the spine to form the book block. Before the covers were bound to the book, the block of text pages was sometimes trimmed along the three unbound edges to open the folds of the paper and to produce smooth edges for the book.