The Romans created the first items we would call books rather than scrolls, but it wasn't until the time of Johann Gutenberg and his printing press in the mid-1400s that books could be reproduced regularly and uniformly. Gutenberg and his successors standardized printing, which included standard type, page sizes, page numbers and contents. The books generally were printed in signatures, or small booklets of a set, even number of pages. They were printed front and back with appropriate pages. When all the pages of a signature were printed, they would be folded along the middle. To make a 96-page book, you would need 8 signatures of 12 pages each. These then were lined up in the correct order and sewn together as one book. Hardcovers and a cloth spine were added to create a full book.
The hardcover book was the standard until paper got cheaper. This happened in the late 1800s when newsprint and pulp paper came into being. This cheap paper allowed the creation of the multitude of newspapers that sprang up and allowed the creation of the cheap magazine, or "pulp." To create pulp magazines and the "dime" novels, the same signature technique was used, but instead of sewing them together in a cloth binding, the signatures were spread with glue on their spines. The glued signatures then were affixed to wraparound covers, usually of a heavier stock.
The creation of these glued magazines caused a groundswell of interest in reading for entertainment by the masses. These perfect-bound magazines began with Frank Munsey to dominate an as-yet untapped market. The pulps were at the forefront of cheap reading material from the 1890s until they ceased to exist in the mid-1950s. Most pulps were 6-by-9 inch volumes or 8.5-by-11 inch "bedsheet" magazines.
The first mass-market perfect-bound books, which came to be known as paperbacks, were produced in the early 1930s. It wasn't until the 1950s, however, that they reached widespread popularity. This happened because they were cheaper to produce and to buy, which led to a secondary market for hardcover books and a new market for works first published in paperback form. In some genres, such as science fiction, for example, publishers could not justify the cost of producing a full hardcover book, but could justify the cost of a paperback.
Perfect binding can be done from the computer desktop, too, but the old-fashion page presses and glue still are needed to complete the volume. It is far simpler and cheaper to produce saddle-stitched (stapled) small press books (chapbooks) since this all can be done on the computer with a printer and an oversized stapler. To produce a perfect bound book, however, the computer part is the same. The book is laid out and designed in the computer, then printed to sheets of paper in signatures. The signatures then are placed in the correct order and placed in a vice or press that squishes the pages together while leaving the signature spines exposed. You apply glue to the spines, then attach the cover. The cover must be big enough to cover the spine and both sides of the book. Once attached, the entire book with covers again is placed in the press or vice for sometime to give the glue time to try without undue pressure from the book itself.
Once the book is perfect bound, the last thing to do is get it face-trimmed. The pages will be uneven because each page of each signature is pushed out slightly by the preceding signature. This means a home-made perfect bound book won't look that perfect. This is a nearly impossible task at home, unless you happen to have a face-trimming machine in the basement. The easy and inexpensive solution is to go to a local small printer who can face-trim books and pay the printer to do it. This one small step will give a very professional-looking final book.