Thread sewn binding is the oldest type of book binding. Accordingly, many methods and types have developed over the centuries, such as saddle stitching, block stitching, alternate stitching, and many more.
In thread sewn binding, the folded sheets are sewn together at the spine to form a book block. The thickness of the thread must always match the paper of the book block. Four (in rare cases also eight) sheets are sewn together in each case to form a layer and then knotted together to form a book block. It is important that the stitching tapes are not pierced during stitching so that there is no tension when the spine is rounded later. Stitching tapes can be made of parchment, leather or fabric, among other materials.