An Incunabulum (plural incunabula, from the Latin in cuna, "in the cradle") is a book that was printed in the 15th century, that is, in the period between the first work of Johann Gutenberg (around 1450) and the year 1500.
About a third of the incunabula that are preserved today belong to the Vatican Library.
The gradual spread of printing ensured that there was great variety in the texts chosen for printing and the styles in which they appeared. Many early typefaces were modelled on local forms of writing or derived from the various European forms of Gothic script, but there were also some derived from documentary scripts (such as most of Caxton's types), and, particularly in Italy, types modelled on humanistic hands. Printers tended to congregate in urban centres where there were scholars, ecclesiastics, lawyers, nobles and professionals who formed their major customer-base. Generally speaking, standard works in Latin inherited from the medieval tradition formed the bulk of the earliest printing, but as books became cheaper, works in the various vernaculars (or translations of standard works) began to appear.
The tally of editions and titles issued before 1500 runs into thousands, and the most authoritative listing is in the German catalogue, the Gesamtkatalog der Wiegendrucke which is still being compiled; but other reference works such as the series of catalogues of the holdings of the British Library are also useful.