incunabula refers to a printed book (not written) before the year 1501. now this is pretty arbitrary. there are two kinds of incunabula, (1) the woodcut, called xylography, and (2) the subsequent "typographic book," made with movable print. (2) is preferred to (1).
as a geographical distribution:
see that as we move to 1500 the printing process spreads all over western europe for a total of about 282 towns!
title pages start appearing circa 1480
like medieval manuscripts, early incunabula did not have title pages (the high cost of animal skin used as the medium did not allow the waste of any part of the material for other than the text). instead, the title, author's name, transcriber's name, place and year of transcription and other related matters were written at the end of the manuscripts.
following the design of manuscripts, printers of incunabula also had the first letter (initial) of the first word of each chapter in large size and in red ink. in the process of printing, the corresponding part of the page for the initial was left blank, and later, a craftsman called a "rubricator" drew a decorative initial in that space. to designate the letter to be drawn, a small form of the letter was sometimes printed in the space beforehand. this small printed letter is called the "guide letter."
1- rubrication: an important process, at the beginning of the page. the capital, the beginning. the process is that the corresponding part of the page for the the R. was left blank, and later, a craftsman called a "rubricator" drew a decorative initial in that space. see that in the text above there is the rubricator and smaller capitals.
2- marginalia: this is kind of our modern end notes in the margin, they provide info, i.e., source of quoted sentences, usually in smaller size types than those used for the main text.
3- double columns: these are explanatory texts around the text, one informs the other.
4- colophon: instead, the title, author's name, transcriber's name, place and year of transcription and other related matters at the beginning, the practice is to have it at the end of the manuscripts (to save paper, which is very expensive). a colophon page below.
(All images and text taken from INCUNABULA).