USMARC (US Machine-Readable Cataloging) is a set of standards for creating and formatting bibliographic records for library materials. It was developed by the Library of Congress in the late 1960s and early 1970s, and has been widely adopted by libraries in the United States and around the world. The USMARC format is a machine-readable format, which means that it is designed to be used by computer systems to store and retrieve bibliographic information.
The USMARC format includes a set of data elements, such as title, author, publication date, and subject headings, that are used to describe the resource. The format also includes a set of rules for how the data elements should be organized and formatted, so that the information can be easily understood by both humans and computer systems.
The USMARC format is divided into three main parts: the leader, the directory, and the variable fields. The leader contains information about the bibliographic record, such as its length and the type of resource it describes. The directory contains information about the location of the variable fields within the record. The variable fields contain the actual data elements of the bibliographic record, such as the title, author, publication date, and subject headings.
USMARC is widely used in libraries, and it is one of the most common formats for bibliographic records, especially in the US. However, with the increasing use of linked data and the need for data to be more interoperable, USMARC is being replaced by other formats such as RDF, BIBFRAME and schema.org