A hardcover, hardbound book has rigid covers and is stitched in the spine. Looking from the top of the spine, the book can be seen to consist of a number of signatures bound together. When the book is opened in the middle of a signature, the binding threads are visible. Signatures of hardcover books are typically octavo (a single sheet folded three times), though they may also be folio, quarto, or 16mo (see Book size). Unusually large and heavy books are sometimes bound with wire.

Until the mid-20th century, covers of mass-produced books were laid with cloth, but from that period onward, most publishers adopted clothette, a kind of textured paper which vaguely resembles cloth but is easily differentiated on close inspection. Most cloth-bound books are now half-and-half covers with cloth covering only the spine. In that case, the cover has a paper overlap. The covers of modern hardback books are made of thick cardboard..

Library binding refers to the hardcover binding of books intended for the rigors of library use and are largely serials and paperback publications. Though many publishers have started to provide "library binding" editions, many libraries elect to purchase paperbacks and have them rebound as hardcover books, resulting in longer life for the material.