UNIMARC is maintained by the Permanent UNIMARC Committee of the International Federation of Library Associations and Institutions (IFLA), and is widely used in Europe. There are several versions of MARC in use around the world, the most predominant being MARC 21, created in 1999 as a result of the harmonization of U.S. Two years later, they became the international standard.

By 1971, MARC formats had become the US national standard for dissemination of bibliographic data. Working with the Library of Congress, American computer scientist Henriette Avram developed MARC during 1965–1968 to create records that could be read by computers and shared among libraries. Other standards work in conjunction with MARC, for example, Anglo-American Cataloguing Rules (AACR)/ Resource Description and Access (RDA) provide guidelines on formulating bibliographic data into the MARC record structure, while the International Standard Bibliographic Description (ISBD) provides guidelines for displaying MARC records in a standard, human-readable form. The structure of bibliographic records almost universally follows the MARC standard. Computerized library catalogs and library management software need to structure their catalog records as per an industry-wide standard, which is MARC, so that bibliographic information can be shared freely between computers. MARC ( machine-readable cataloging) is a standard set of digital formats for the machine-readable description of items catalogued by libraries, such as books, DVDs, and digital resources.

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