Books and booklets can be made by sewing together the spine of the signatures (printed paper folded into the size of the book) with thread. This technique is called itotoji (sewn binding) or kagari. Because books made this way are strong and can be opened to the gutter, this is the most orthodox method of binding signatures into a booklet form.

The binding process can be carried out on a machine or by hand, but mass-produced publications are mostly bound mechanically. Hand bound books are usually made as craft work. Methods for sewing the signatures together differ depending on whether the book is bound mechanically or manually, but there are also several ways of sewing hand bound books too. The thread used is normally made of cotton or hemp, and the thickness of the thread and the number of times it is threaded through the signatures depends on the size of the book and the type of paper it is made from. Large and thick books may have a cotton or hemp tape sewn into the spine to enhance the binding strength.