Evolving from paper ""card catalogues"", MARC (MAchine Readable Catalog) records make the vast network of information-sharing, interlibrary loans, system and consortia data communication possible. MARC records, created in tandem with the Anglo-American Cataloguing Rules, hold the keys to information for librarians and library users alike. Using common conventions and a shared language of tags, subfields, indicators and codes, MARC 21 - the latest code at time of publication - is a powerful integrated record format packed with information so all librarians can do their work more effectively. Covering both the big-picture fundamentals and the basics of nuts-and-bolts details, this volume offers an introduction to MARC 21. Including self-assessment tools such as quizzes, tables, and many examples of tags and subfields, it addresses: how to search MARC records; what the terms and codes mean; how different library departments use MARC; and how MARC record data should be presented to end users.