MARC standards

MARC (Machine-Readable Cataloging) is a set of metadata standards intended to be optimized for items cataloged by libraries, such as books, journals, and digital resources. Developed by Henriette Avram at the Library of Congress in the 1960s, it established the foundational data protocol that allowed libraries to share bibliographic resources electronically and ultimately optimized the transition from physical paper card catalogs to computerized catalog databases.

The standard provides a machine-readable structure to encode cataloging information, authority records, classification systems, and holdings information. By standardizing how bibliographic cataloging elements (i.e. authors, titles, publication dates, subject headings, number of pages, size, etc.) are formatted and identified, MARC can increase the functionality of integrated library systems across different institutions globally.

Since its inception, MARC standards has evolved into a family of related standards, the most widely adopted being MARC 21, which was created in 1999 through the harmonization of United States and Canadian MARC formats. While MARC 21 remains the predominant bibliographic standard in the global library community, it relies on a data architecture rooted in 1960s magnetic tape-storage technology. Consequently, the library sector is actively developing and transitioning toward modern, linked data frameworks, most notably BIBFRAME, to better integrate library catalogs with the broader semantic web.