Book printing terms, explained

The words printers use, in plain language, with why each one matters for your book.

Barcode (EAN): The scannable barcode on the back cover that encodes your ISBN and sometimes the price.
Bleed: Extra art that runs past the edge of the page, so a slightly off cut never leaves a white sliver.
Book block: All the inside pages of a book, bound together, before the cover goes on.
Case wrap (case binding): A hardcover whose printed cover is wrapped around rigid boards.
CMYK: The four ink colors used in print: cyan, magenta, yellow and black.
Coated and uncoated paper: Coated paper has a smooth finish for crisp color. Uncoated paper is soft, natural and easy to read.
DPI (dots per inch): How many image pixels land in each printed inch. Aim for about 300 for sharp printed images.
Dust jacket: A loose printed paper cover that wraps a hardcover, with flaps that fold inside.
Embossing and debossing: Pressing a design into the cover so it stands raised (emboss) or sits recessed (deboss).
Endpapers: The sturdy sheets that join a hardcover's pages to its case, front and back.
Foil stamping: Metallic foil pressed onto a cover, such as a gold or silver title.
Front matter: The pages before chapter one: title page, copyright page, dedication and contents.
GSM: Grams per square meter: the weight of a paper, and a rough guide to how thick it feels.
Gutter: The inside margin where facing pages meet at the spine.
Head and tail bands: Small decorative bands at the top and bottom of a hardcover's spine.
ISBN: The 13 digit number that identifies one format of one book.
Lamination: A thin protective film on the cover: matte, gloss or soft touch.
PDF/X: A standard kind of PDF made for printing, with fonts and images built in.
Perfect binding: The usual paperback binding: pages glued into a wraparound cover at the spine.
PPI (pages per inch): How many pages of a paper stack up to one inch. Used to work out spine width.
Print run: The number of copies printed at one time.
Proof: A preview of your book to check before it prints: digital or printed.
Recto and verso: Recto is a right-hand page. Verso is a left-hand page.
Safe area: The zone inside the trim where words and important details are sure to print in full.
Signature: A group of pages printed on one large sheet, then folded and trimmed together.
Smyth sewn (section sewn): A strong binding where folded sections of pages are stitched together through the fold.
Spine width: How thick your book's spine is, set by your page count, paper and binding.
Spot UV: A clear glossy coating applied to just part of a cover, like a title.
Trim size: The finished size of your book after it is cut, such as 6 x 9 inches.