noun
colophon; imprint; publication information
Refers to the page at the end of a book that lists the publisher, date of publication, author, and other bibliographic details.
この本の奥付を見ると、発行日は去年の三月だとわかる。
Looking at the colophon of this book, you can see that the publication date is March of last year.
奥付には出版社の住所
The publisher's address is also listed in the colophon.
奥書 is a broader term for any writing at the end of a book, often handwritten notes or postscripts, while 奥付 specifically refers to the printed publication data.
Compound of 奥 (oku, 'back, interior') and 付 (tsuke, 'attached'), referring to the information attached at the back of a book.