Signature
A large printed sheet folded into a group of pages (often 16 or 32) that is then bound. Why page counts come in multiples of 4.
More in Book anatomy
Back matter
Everything after the main text: appendices, notes, glossary, bibliography, index, acknowledgements and author bio.
Colophon
A note (often at the back) describing the book's production — typeface, paper, printer. Historically, a publisher's emblem.
Copyright page
The verso of the title page, holding copyright notice, ISBN, edition, publisher details and legal lines. Also called the imprint page.
Dust jacket
The removable printed paper cover wrapped around a hardback, with flaps for blurb and author bio.
Endpapers
The sheets that join the book block to a hardcover case, glued inside the front and back boards.
Epigraph
A short quotation at the start of a book or chapter that sets a tone or theme.