complete "book" is collected together in one stack, next to another, and another.

the methods used for the printing and binding of books continued fundamentally unchanged from the 15th century into the early 20th century. While there was more mechanization, a book printer in 1900 had much in common with Gutenberg.
Gutenberg's invention was the use of movable metal types, assembled into words, lines, and pages and then printed by letterpress to create multiple copies.
Modern paper books are printed on papers designed specifically for printed books. Traditionally, book papers are off-white or low-white papers (easier to read), are opaque to minimise the show-through of text from one side of the page to the other and are (usually) made to tighter caliper or thickness specifications, particularly for case-bound books. Different paper qualities are used depending on the type of book: Machine finished coated papers, woodfree uncoated papers, coated fine papers and special fine papers are common paper grades.
Today, the majority of books are printed by offset lithography. When a book is printed the pages are laid out on the plate so that after the printed sheet is folded the pages will be in the correct sequence. Books tend to be manufactured nowadays in a few standard sizes. The sizes of books are usually specified as "trim size": the size of the page after the sheet has been folded and trimmed. The standard sizes result from sheet sizes (therefore machine sizes) which became popular 200 or 300 years ago, and have come to dominate the industry. British conventions in this regard prevail throughout the English-speaking world, except for the USA. The European book manufacturing industry works to a completely different set of standards.
Current processes


Book covers
Some books, particularly those with shorter runs (i.e. fewer copies) will be printed on sheet-fed offset presses, but most books are now printed on web presses, which are fed by a continuous roll of paper, and can consequently print more copies in a shorter time. As the production line circulates, a complete "book" is collected together in one stack, next to another, and another.
A web press carries out the folding itself, delivering bundles of signatures (sections) ready to go into the gathering line. Notice that when the book is being printed it is being printed one (or two) signatures at a time, not one complete book at a time. Excess numbers are printed to make up for any spoilage due to "make-readies" or test pages to assure final print quality.
A make-ready is the preparatory work carried out by the pressmen to get the printing press up to the required quality of impression. Included in make-ready is the time taken to mount the plate onto the machine, clean up any mess from the previous job, and get the press up to speed. As soon as the pressman decides that the printing is correct, all the make-ready sheets will be discarded, and the press will start making books. Similar make readies take place in the folding and binding areas, each involving spoilage of paper.
After the signatures are folded and gathered, they move into the bindery. In the middle of last century there were still many trade binders – stand-alone binding companies which did no printing, specializing in binding alone. At that time, because of the dominance of letterpress printing, typesetting and printing took place in one location, and binding in a different factory. When type was all metal, a typical book's worth of type would be bulky, fragile and heavy. The less it was moved in this condition the better: so printing would be carried out in the same location as the typesetting. Printed sheets on the other hand could easily be moved. Now, because of increasing computerization of preparing a book for the printer, the typesetting part of the job has flowed upstream, where it is done either by separately contracting companies working for the publisher, by the publishers themselves, or even by the authors. Mergers in the book manufacturing industry mean that it is now unusual to find a bindery which is not also involved in book printing (and vice versa).
If the book is a hardback its path through the bindery will involve more points of activity than if it is a paperback.
Unsewn binding, is now increasingly common. The signatures of a book can also be held together by "Smyth sewing" using needles, "McCain sewing", using drilled holes often used in schoolbook binding, or "notch binding", where gashes about an inch long are made at intervals through the fold in the spine of each signature. The rest of the binding process is similar in all instances. Sewn and notch bound books can be bound as either hardbacks or paperbacks.