What's a "colophon"?
Modern usage treats any trademarked publisher's image as a "colophon," but bibliographic historians reserve the word for an early print edition's way of identifying who printed the book, when, and where. The word is derived through Latin from a Greek word for "summit," and means, metaphorically, a "final gesture or crowning achievement." That function is performed at the bottom of title pages in books printed after the early 1500s, but during the first half-century of printing (c. 1440-1500), printers followed manuscript practices and put it at the end of the book. Monks typically indicated the beginning of a text in manuscript with the phrase "Incipit [title]" ("here begins [title]) such as "Incipit Matthew" for the first of the Gospels, and they ended the text "Explicit [title]" ("here ends [title]"), sometimes telling readers at that point who had finished the copy and when. (Follow the hyperlink to see Sir Thomas Malory's extraordinarily informative final explicit to his Morte Darthur [MS 1469/70, 1st edition, 1485].) The scribes, and perhaps some authors, appear to have used the convention to assure readers they had actually acquired a full copy of the work, and sometimes the "incipit" or "explicit" becomes firmly attached to the work, itself, as in the case of all surviving copies of Chaucer's Troilus, which end, "Explicit liber Troili et Criseide," and "Canterbury Tales" manuscripts which begin "Here bygynneth the Book of the Tales of Caunterbury" (RC 585 & 23) Similar information about who printed the book, often including in what place and year, the earliest printers set in type at the end of their books, like this page concluding John Day's 1567 edition of Aelfric's A Testimony of Antiqvity shewing the ancient Fayth in the Church of England (Bright Collection 41519). This is rather late for a colophon! Note the Latin assertion of Royal permission to print, which indicates the book was registered with the Stationers' Company, the printers and book publishers' guild that censored printing in England in return for a royal monopoly on the operation of presses.