“MAchine Readable Cataloging-a standard format for bibliographic records. (A catalog card is an example of a bibliographic record.)
Translation: the information about a book or other item, in the same form as that used by everyone else cataloging books, so computers can read the record. This standardized format means that any system which is MARC-compatible can read and interpret the information in exactly the same way, no matter which system was used to create the MARC record, or which system is reading the record. (Most library automation systems are MARC-based–don’t buy one that isn’t.)
MARC records have pieces of information “”tagged,”” or labeled in such a way that the software reading them knows exactly what kind of information it’s looking for, or looking at. For example, we know John Grisham as an author; the MARC record tags John Grisham as 100 (or main entry–personal name field); what we call a title is MARC’s 245. The MARC tag is also used by the computer software to locate the piece of information within the bibliographic record. This system allows computers to work with the information more efficiently.
The good news is that catalogers don’t have to know exactly how the computer finds the information but they do need to know where to put the information, and how to tag it, so that the computer can do its job.”