library

A view of the Library of Congress, situated in the Capitol Building, Washington, DC, USA. Founded in 1800, it now contains well over 17 million books and in excess of 95 million maps, manuscripts, and other media items.

Collection of information held for common use. The earliest was in Nineveh in Babylonian times. The first public library was opened in Athens in 330 BC. All ancient libraries were reference libraries: books could be consulted but not borrowed. Lending or circulating libraries did not become popular until the 18th century; they became widespread in the 19th century with the rapid development of public libraries. Free public libraries probably began in the 15th century. In the UK, the first documented free public library was established in Manchester in 1852, after the 1850 Public Library Act. The first free, public, tax-supported library in the USA was opened in Boston in 1854.

Classification Books have, as a rule, been grouped according to contemporary scholastic disciplines. The first catalogue of the Bodleian Library, Oxford, published in 1605, shows that the library was arranged according to the four faculties into which studies at the University of Oxford were then divided: theology, medicine, law, and arts. As subjects of study have diversified and multiplied, classification has been extended to take in new subjects and divisions and combinations of existing subjects.

Books are usually classified by one of two major systems: the Dewey Decimal Classification (now known as Universal Decimal Classification), invented in the USA by Melvil Dewey, and the Library of Congress system. Most library cataloguing systems changed around the end of the 20th century, and range from cards or microfiche to computer databases with on-line terminals. These frequently make use of ISBN numbers (International Standard Book Numbers) and, for magazines and journals, ISSN numbers.

Cataloguing Catalogues originally listed books after they had been placed on the library shelves, hence early catalogues were nearly always in some classified sequence. From the 17th century onwards a catalogue arranged in alphabetical order of authors' names came to be regarded as the library's main catalogue. The author catalogue is generally supplemented by a full or partial subject catalogue, arranged in either classified or alphabetical order of subjects. A typical catalogue entry gives the author's name, the book's title, edition, and imprint, and possibly also a note on its subject matter or its publishing history, and indicates where the book is to be found in the library.

Public libraries did not usually permit open access to their shelves until the early years of the 20th century; many national and university libraries, on account of the size and value of their collections, still restrict access.

The form of the catalogue varied according to its purpose and the materials and techniques available for its compilation. As parchment was scarce and costly in the Middle Ages, catalogues were often written in odd blank spaces or on a spare page of some manuscript kept in the library. Only the librarian (in monastic libraries usually the precentor, who had charge of music and service books) would need to use such a list to check the books in his care. After printing had become common and the use of libraries had become more general, library catalogues were issued as printed volumes. Printed catalogues had two advantages: they could be consulted outside the library, and, if they described a great or specialized collection of books, they formed valuable bibliographies.

The accelerated growth of library collections and the mounting cost of printing led to the replacement or supplementation of the printed catalogue by either a catalogue on paper slips kept in binders, a sheaf catalogue, or a catalogue on cards kept in a cabinet of drawers. This was easy to consult and to keep up to date with insertions, withdrawals, and replacements of worn cards, but its maintenance was costly and its size could be cumbersome. Developments in photography made it possible to reproduce card catalogues in printed book form. Electronic data processing used in conjunction with microphotography has made it possible to issue updated catalogues in the form of loose-leaf books, or to store a library's complete, updated catalogue on microfilm for display on screens (readers). These in turn were replaced by computer cataloguing systems from the late 1980s, which made management and exchange of collections easier, less expensive, and more up-to-date. At the same time, electronic publications began to enter library collections. Modern libraries also often include CDs and DVDs.

The American Library Association was founded in 1876, the Library Association, UK, in 1877.