At Uppsala University Library we use the expression older books or early imprints for materials printed before the end of 1850. 

There are large collections of early imprints at Carolina Rediviva that have been collected through donations and purchases since the 17th century. The cut-off point at 1850 for defining "early imprints" is rather arbitrary but it is practical at the Library where special rules apply to the handling of these books. For instance they are not available for home loans and can be studied only in the Special Reading Room.

Historically the choice of year represents a transition in printing processes and the technical production of paper. Book production went over from printing on high quality paper using handpresses to mass production. This took place in the West during the industrial revolution in the latter half of the 19th century.

The University Library's collections of early imprints include books that were printed right from the start of book printing in the 15th century. In the exhibition hall at Carolina Rediviva you can see, for example, Sweden's oldest printed book, Dyalogus creaturarum moralizatus ("The dialogues of creatures moralysed"). It was printed in Stockholm in 1483. You can also see the first book published in the Swedish language, Aff dyäffwlsens frästilse ("On the temptations of the devil"). This was printed in 1495. 

Printed books published in the 15th century, before the end of 1500, are called incunables. The word comes from Latin "incunabula" which means swaddling clothes or infancy.  Thus they are books from the earliest days of the printing press. Uppsala University Library holds around 2,500 such works. 

Among them is the greater part of Copernicus' own library. These books were brought to Sweden as war booty during the Thirty Years' War. 

Read more about the University Library's early imprints and special collections.