A library catalog (or library catalogue in British English) is a register of all bibliographic items found in a library or group of libraries, such as a network of libraries at several locations. A catalog for a group of libraries is also called a union catalog. A bibliographic item can be any information entity (e.g., books, computer files, graphics, realia, cartographic materials, etc.) that is considered library material (e.g., a single novel in an anthology), or a group of library materials (e.g., a trilogy), or linked from the catalog (e.g., a webpage) as far as it is relevant to the catalog and to the users (patrons) of the library.
The card catalog was a familiar sight to library users for generations, but it has been effectively replaced by the online public access catalog (OPAC). Some still refer to the online catalog as a "card catalog". Some libraries with OPAC access still have card catalogs on site, but these are now strictly a secondary resource and are seldom updated. Many libraries that retain their physical card catalog will post a sign advising the last year that the card catalog was updated. Some libraries have eliminated their card catalog in favor of the OPAC for the purpose of saving space for other use, such as additional shelving.
The largest international library catalog in the world is the WorldCat union catalog managed by the non-profit library cooperative OCLC. In January 2021, WorldCat had over half a billion catalog records and three billion library holdings.
Goal
Antonio Genesio Maria Panizzi in 1841 and Charles Ammi Cutter in 1876 undertook pioneering work in the definition of early cataloging rule sets formulated according to theoretical models. Cutter made an explicit statement regarding the objectives of a bibliographic system in his Rules for a Printed Dictionary Catalog. According to Cutter, those objectives were
1. to enable a person to find a book of which any of the following is known (Identifying objective): the author the title the subject the date of publication
2. to show what the library has (Collocating objective) by a given author on a given subject in a given kind of literature
3. to assist in the choice of a book (Evaluating objective) as to its edition (bibliographically) as to its character (literary or topical)
These objectives can still be recognized in more modern definitions formulated throughout the 20th century.
Other influential pioneers in this area were Shiyali Ramamrita Ranganathan and Seymour Lubetzky.
Cutter's objectives were revised by Lubetzky and the Conference on Cataloging Principles (CCP) in Paris in 1960/1961, resulting in the Paris Principles (PP).
A more recent attempt to describe a library catalog's functions was made in 1998 with Functional Requirements for Bibliographic Records (FRBR), which defines four user tasks: find, identify, select, and obtain.
A catalog helps to serve as an inventory or bookkeeping of the library's contents. If an item is not found in the catalog, the user may continue their search at another library.
Card
A catalog card is an individual entry in a library catalog containing bibliographic information, including the author's name, title, and location. Eventually the mechanization of the modern era brought the efficiencies of card catalogs. It was around 1780 that the first card catalog appeared in Vienna. It solved the problems of the structural catalogs in marble and clay from ancient times and the later codex—handwritten and bound—catalogs that were manifestly inflexible and presented high costs in editing to reflect a changing collection. The first cards may have been French playing cards, which in the 1700s were blank on one side.
In November 1789, during the dechristianization of France during the French Revolution, the process of collecting all books from religious houses was initiated. Using these books in a new system of public libraries included an inventory of all books. The backs of the playing cards contained the bibliographic information for each book and this inventory became known as the "French Cataloging Code of 1791".