The art and craft of bookmaking long predates photography as an expressive medium. Like any discipline, book design/publishing comes with its own nomenclature. Below are some common terms that you may encounter when you begin making and publishing photo books.
Accordion (Concertina) Fold: Parallel folds that open up like an accordion.
Addendum: Information added to the end of a book after publication.
Appendix: Supplemental information added to the end of a book (tables, glossary, bibliography, etc.).
Awl: A tool used for piercing paper to produce pathways for thread when sewing a text block. For best results, an awl should be just slightly larger than the needle used for sewing.
Back Matter: Refers to the appendix, index, and colophon at the end of a book.
Bench Sewing: Sewing through a fold to combine signatures into a text block.
Bleed: Edge of the page that is trimmed. If you want images to extend all the way to the edge of your page, you should allow them to extend a bit into the bleed, so you don’t get a thin white line at the edge of the page.
Bone Folder: A tool used for folding creases to produce crisp folded edges.