The “ICD-10-CM Expert for Hospitals with Guidelines 2021” by Optum360 is a comprehensive textbook in trade paperback format focused on the medical coding and billing subject area. Published in 2020 by Optuminsight, Incorporated, this book is designed for allied health services professionals looking to deepen their understanding of ICD-10-CM regulations and guidelines. Written in English by the author Optum360, this textbook is an essential resource for those seeking to enhance their knowledge and skills in medical coding and billing within the hospital setting.