Machine-readable Record Format 

MARC  is an acronym  for Machine-readable Catalogue or cataloguing. This general description is misleading, implying that MARC is a kind of catalogue or method of cataloguing. Whereas  MARC  is more accurately  defined as  a  group of formats employing a  particular set of  conventions for the identification and arrangement of bibliographic data for handling by computer. 

The original MARC format, from which current formats originated was developed at the Library of Congress in 1965-66. Since then more than 20 formats have appeared which are known as MARC. Their common characteristics are: 

1. adherence to the ISO 2709 record structure, or its equivalent national standard, including option which allows use of indicators and subfield identifiers in data fields. 
2. most of them are national formats based in national library or national bibliographic agency and are designated communication formats for exchange of bibliographic records , with other similar organisations. 

MARC records have many other library and  non-library related uses, though it is generally identified with the production of library catalogues and national bibliographies. Library of Congress (LC) was the first to design and experiment on a machine-readable catalogue (MARC) record format for the purpose of communication bibliographic information to a large number of libraries. When MARC-I commenced as a pilot project in 1966 in LC, there were no established MARC formats available. Libraries had reached no consensus as to which access points were required to  take full advantage of an automated cataloguing system. During November 1966 to June 1967 sixteen libraries took part in  developing early MARC format for English language monographs/books only on experimental basis. 

The format MARC-II was a considerably improved one in the light of experiences and opinions of important libraries and a specific survey carried out for studying the requirements of the user.  MARC  II format developed in  1968  was the result of Anglo-American co-operation. The new format was intended to be hospitable to  all kinds of library materials; sufficiently flexible for a variety of applications in addition to  catalogue production; and usable in  a range of  different computer systems. Despite Anglo-American cooperation there were two versions of MARC, i.e., LC MARC II and BNB MARC II.