Perfect binding
The common paperback method: pages glued at the spine into a squared-off cover. Most POD books are perfect-bound.
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Case binding
Hardcover binding: the book block is sewn or glued into rigid boards (the 'case'). Durable and premium.
CMYK
The four ink colours used in printing — Cyan, Magenta, Yellow, Key (black). Print files should be CMYK, not screen RGB.
Coated / uncoated
Coated paper has a smooth (matte or gloss) surface for crisp images; uncoated is more natural and easier to read for long text.
Crop marks
Thin lines outside the trim showing where to cut. Paired with bleed.
DPI / PPI
Dots/pixels per inch — image resolution. Print images should be 300 DPI at final size; 'PPI' also means a paper's pages-per-inch.
Emboss / deboss
Raising (emboss) or recessing (deboss) an image or text into the cover for a tactile effect.