Synopsis MARC 21, ISO 2709 communication format is the name of harmonized CAN/MARC and USMARC format, it is designed to facilitate the exchange of bibliographic and related information. It is an International exchange format, and supports the revised Anglo American Cataloguing rules (AACR-II, 2 ed, 2002 revision). In this format a proper place is provided for each of the bibliographic information, if a bibliographic record has been marked correctly and saved in a computer data file, computer programs can then be written to search for an retrieve certain types of information within a specific fields, and also to display lists of items meeting the search criteria. Computer can read and interpret the data or information traditionally shown on a catalog card as Author, title, subject heading, and publishers etc. This book consists the MARC 21 concise format for Bibliographic Authority and Holding Data.