MARC is an acronym for Machine-Readable Catalogue or Cataloguing. It is not, however, a kind of catalogue nor a method of cataloguing but a system by which data elements within bibliographic records are uniquely labeled for computer handling. MARC is an implementation of the international standard "Information and documentation - Format for information exchange". (ISO 2709-1996)Applications and functions
MARC is widely used by libraries and other information agencies to exchange bibliographic and related information between systems. In addition, the specificity provided by the use of MARC fields and sub-fields as labels for data elements comprising bibliographic records facilitates the retrieval and manipulation of information in automated information systems. For example, most online systems offer different levels of detail in displays of bibliographic records; the user may be interested in viewing the full MARC record or a brief record. Sorting is an important issue for systems; a user may choose which data elements to use in the sorting of information. Searching in an online environment has also become more efficient and effective with systems offering users a wide range of search keys and the opportunity for combining search terms. Originally, MARC was designed to support the distribution of bibliographic information on magnetic tape. Today, MARC records may be available on any number of different media including diskette and CD-ROM and may be transmitted via file transfer and other forms of direct computer-to-computer communications. While MARC was originally designed for bibliographic data, the principles are now applied also to authority control, classification and community information, for which non-bibliographic formats now exist.
Largely for historic reasons, there are several different national MARC formats. Although these national formats have much in common they are sufficiently different to require conversion programs between them. IFLA's UNIMARC format was primarily designed as an intermediate format, to reduce the number of conversion programs, which a library might, need in order to utilize records from different sources.
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