Normally books with very many pages are sewn due to durability of sewing. Paperback or soft cover books are normally bound using perfect binding.
Normally books with very many pages are sewn due to durability of sewing. Sewn books don’t fall apart and don’t lose pages. Each signature is sewn individually with threads going through each page several times. The threads are then tied off. All of the signatures are likewise attached together with thread creating what is called the book block. Spines of sewn book blocks can be better rounded than spines of glued book block and rounding also stays longer.
Paperback or soft cover books are normally bound using perfect binding. They consist of folded, gathered signatures and possible inserts with a cover made from heavier paper, glued together at the spine with strong flexible glue. The sections are rough-cut in the back to make them absorb the hot glue. The other three sides are then face trimmed. This is what allows a book to be opened. Perfect binding is the cheapest binding option.