The ISO 27000 standard series and IT baseline protection are becoming increasingly important for companies and authorities that want to implement and operate IT security management within their organization. In an international context, the application of ISO 27001 is nearly indispensable for many organizations. This book guides the reader step by step through these standards and explains clearly how to establish an adequate management system (ISMS) and analyze and assess existing risks. The thoroughly commented controls assist security officers in selecting appropriate security measures across all areas. The use of key figures to measure security is illustrated with examples. Additionally, the reader receives detailed information on internal and external audits as well as certification according to ISO 27001. This expanded fourth edition of the book takes these aspects into account.