This document introduces the fourth edition of The Concise AACR2, which provides a simplified version of the Anglo-American Cataloguing Rules (AACR2) intended for cataloguing students, librarians in small libraries, and others who do not need the full complexity and detail of AACR2. The Concise AACR2 presents the commonly applicable descriptive cataloging rules from AACR2 in a rewritten, simplified form with new examples, while referring users to AACR2 for problems not covered and for fuller explanations. It aims to convey the essence and basic principles of AACR2 cataloging practice in a more accessible way.