In the years that immediately followed the invention of the printing press, printers copied the only book models that they knew – manuscripts. As a matter of course, they reproduced the writing, layout and organisation of the medieval book.
Like manuscripts, the first printed books did not have a title page: the text started on the very first sheet. Their type imitated handwriting, and their layout was the same as their medieval predecessors. Large-format books were composed in columns; sometimes a very lengthy commentary, or gloss, printed in small type would completely surround the text, as was done in medieval manuscripts. The text was often dense, and included abbreviations that would have been used by copyists in the Middle Ages.
The first printed books copied both the handwriting and the design of medieval manuscripts.
Nor was it unusual to hand printed books off to illuminators, who would decorate them in the same way as they would manuscripts. Some printers continued to print certain editions on parchment. Although the printing press was perfected by 1455, the printed book only became distinct from the manuscript slowly and progressively.
Historians and bibliophiles thus invented the concept of incunabula, whose Latin root means "cradle". It is used to designate books printed before 1 January 1501. Despite this artificial and backward-looking nature of this term, it allows us to make a distinction between the oldest printed works, which retain the physical characteristics of manuscripts, and more modern productions. However, it does not exactly correspond to reality, as the design of printed books really came into its own in the 1520s.