This book is a comprehensive guide to the Information Security Management System (ISMS) based on ISO 27001. Information security is now essential for all organizations, and this book is an essential companion to understanding, implementing and improving an ISMS compliant with the international ISO 27001 standard. ISMS goes beyond simple rules and aims to protect sensitive information, manage security risks and promote a culture of continuous improvement. The guide explores in detail the concepts of ISMS, the clauses of ISO 27001 and proposes practical steps for effective implementation. Readers will find detailed information on planning, risk management, certification and much more, with practical advice and real-life examples to help them understand and implement the ISMS. Whether you're an information security professional, an IT manager, a security consultant or simply interested in furthering your knowledge, this guide is for you, and we hope it will become a valuable resource in your journey towards an ISMS.