Editing Library catalog (section)

{{Short description|Register of bibliographic items}}
{{Use American English|date=August 2019}}
{{Use dmy dates|date=July 2021|cs1-dates=y}}
[[File:Yale card catalog.jpg|thumb|The card catalog at [[Yale University]]'s [[Sterling Memorial Library]]]]
[[File:SML-Card-Catalog.jpg|thumb|Another view of the SML card catalog]]
[[File:2010 Manchester UK 4467481691.jpg|thumb|The card catalog in [[Manchester Central Library]]]]

[[File:LOC Main Reading Room Highsmith.jpg|alt=Library of Congress Main Reading Room|thumb|Finding aids are utilized to assist information professionals and help researchers find materials within an archive<ref>{{Citation|last=Highsmith|first=Carol M.|title=Main Reading Room of the Library of Congress in the Thomas Jefferson Building|date=2009|url=https://commons.wikimedia.org/wiki/File:LOC_Main_Reading_Room_Highsmith.jpg#file|access-date=2019-04-20|archive-date=2019-06-15 |archive-url=https://web.archive.org/web/20190615051608/https://commons.wikimedia.org/wiki/File:LOC_Main_Reading_Room_Highsmith.jpg#file|url-status=live}}</ref>]]
[[File:Library Of Congress Card Catalog.jpg|alt=The Card Catalog at the Library of Congress|thumb|The Card Catalog at the Library of Congress]]
A '''library catalog''' (or '''library catalogue''' in [[British English]]) is a register of all [[bibliography|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 (library science)|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 earliest library catalogs were lists, handwritten or enscribed on clay tablets and later scrolls of parchment or paper. As [[codex|codices]] (books with pages) replaced scrolls, so too did library catalogs become like handwritten [[ledger]]s and, in some cases, printed books. During the late 18th century through mid-19th century, cataloguing on paper slips or cards gradually replaced ledgers and books as the main medium for library catalogs, and in the 20th it was long ubiquitous. The '''card catalog''' was a familiar sight to library users for generations. Computerized cataloguing developed gradually from the mid-20th, and by the late 20th and early 21st, it had mostly replaced card catalogs. The advent of the [[World Wide Web|web]] brought about ubiquitous use of [[online public access catalog]]s (OPACs). Some people still informally refer to the online catalog as a "card catalog".<ref>For example, the website of the Childress Public Library in [[Childress, Texas]] refers to its online catalog as a "card catalog": {{cite web |title=Online Card Catalog {{!}} Childress Public Library |url=https://harringtonlc.org/childress/search-for-books/ |website=harringtonlc.org |access-date=2020-09-17 |archive-url=https://web.archive.org/web/20221010151347/https://harringtonlc.org/childress/search-for-books/ |archive-date=2022-10-10 |url-status=dead}} Another example of the term "card catalog" used to refer to an online catalog is in an instructional presentation produced by the Hayner Public Library District, which serves [[Township (United States)|township]]s around [[Alton, Illinois]]: {{cite web |last=Cordes |first=Mary |title=Searching the Card Catalog and Managing Your Library Account Online |url=https://www.haynerlibrary.org/images/Card_Catalog_Instructions_Final_.pdf |website=www.haynerlibrary.org |access-date=2020-09-17 |archive-url=https://web.archive.org/web/20221007103427/https://www.haynerlibrary.org/images/Card_Catalog_Instructions_Final_.pdf |archive-date=2022-10-07 |url-status=dead}}</ref> 

The largest international library catalog in the world is the [[WorldCat]] union catalog managed by the non-profit library cooperative [[OCLC]].<ref name="largest">{{cite book |last=Oswald |first=Godfrey |date=2017 |chapter=Largest unified international library catalog |title=Library world records |edition=3rd |location=Jefferson, NC |publisher=[[McFarland & Company]] |page=291 |isbn=9781476667775 |oclc=959650095 |chapter-url=https://books.google.com/books?id=G4owDwAAQBAJ&pg=PA291}}</ref> In January 2021, WorldCat had over half a billion catalog records and three billion library holdings.<ref>{{Cite web |title=Inside WorldCat |url=https://www.oclc.org/en/worldcat/inside-worldcat.html |website=OCLC  |access-date=2021-03-09 |language=en |archive-date=2017-01-30  |archive-url=https://web.archive.org/web/20170130152208/https://www.oclc.org/en/worldcat/inside-worldcat.html |url-status=live }}</ref>

[[File:Yale VI.JPG|thumb|Card catalog at Yale]]