Saddle stitch staplers or simply saddle staplers are bookbinding

Bookbinding

Bookbinding is the process of physically assembling a book from a number of folded or unfolded sheets of paper or other material. It usually involves attaching covers to the resulting text-block.-Origins of the book:...

 tool

Tool

A tool is a device that can be used to produce an item or achieve a task, but that is not consumed in the process. Informally the word is also used to describe a procedure or process with a specific purpose. Tools that are used in particular fields or activities may have different designations such...

s designed to insert staples into the spine (saddle) of folded printed matter such as booklet

Book

A book is a set or collection of written, printed, illustrated, or blank sheets, made of hot lava, paper, parchment, or other materials, usually fastened together to hinge at one side. A single sheet within a book is called a leaf or leaflet, and each side of a leaf is called a page...

s, catalogues

Mail order

Mail order is a term which describes the buying of goods or services by mail delivery. The buyer places an order for the desired products with the merchant through some remote method such as through a telephone call or web site. Then, the products are delivered to the customer...

, brochure

Brochure

A brochure is a type of leaflet. Brochures are most commonly found at places that tourists frequently visit, such as museums, major shops, and tourist information. Brochure racks or stands may suggest visits to amusement parks and other points of interest...

s, and manuals

Owners manual

An owner's manual is an instructional book or booklet that is supplied with almost all technologically advanced consumer products such as vehicles, home appliances and computer peripherals....

. They are distinguished by their unusual length (most traditional staplers are too short to staple booklets easily) and by the presence of a V-shaped hump or "saddle" which is used to precisely align the central fold of the material to be stapled.

A saddle stapler may also be used to staple fabric or other flexible material, as the material is bunched up inside the throat in order to reach the seam to be stapled.

Most high-end photocopiers and digital production printers

Computer printer

In computing, a printer is a peripheral which produces a text or graphics of documents stored in electronic form, usually on physical print media such as paper or transparencies. Many printers are primarily used as local peripherals, and are attached by a printer cable or, in most new printers, a...

on the market have optional attached saddle stitch units that fold and staple booklets automatically.