Saddle stitch

Bookbinding is the process of physically assembling a book from an ordered stack of paper sheets that are folded together into sections or sometimes left as a stack of individual sheets. The stack is then bound together along one edge by either sewing with thread through the folds or by a layer of flexible adhesive. For protection, the bound stack is either wrapped in a flexible cover or attached to stiff boards. Finally, an attractive cover is adhered to the boards and a label with identifying information is attached to the covers along with additional decoration. Book artists or specialists in book decoration can greatly expand the previous explanation to include book like objects of visual art with high value and artistic merit of exceptional quality in addition to the book's content of text and illustrations.

Before the computer age, the bookbinding trade involved two divisions. First, there was Stationery binding (known as vellum binding in the trade) which deals with making new books to be written into and intended for handwritten entries such as accounting ledgers, business journals, blank books, and guest log books, along with other general office stationery such as note books, manifold books, day books, diaries, portfolios, etc. Second was Letterpress binding which deals with making new books intended to be read from and includes library binding, fine binding, edition binding, and publisher's bindings. A result of the new bindings is a third division dealing with the repair, restoration, and conservation of old used bindings. With the digital age, personal computers have replaced the pen and paper based accounting that used to drive most of the work in the stationery binding industry.

Today, modern bookbinding is divided between hand binding by individual craftsmen working in a one-room studio shop and commercial bindings mass-produced by high speed machines in a production line factory. There is a broad grey area between the two divisions. The size and complexity of a bindery shop varies with job types, for example, from one of a kind custom jobs, to repair/restoration work, to library rebinding, to preservation binding, to small edition binding, to extra binding, and finally to large run publisher's binding. There are cases where the printing and binding jobs are combined in one shop. A step up to the next level of mechanization is determined by economics of scale until you reach production runs of ten thousand copies or more in a factory employing a dozen or more workers.

...
Wikipedia