A must-have rapid reference tool for enterprise Operations Security (OPSEC) practitioners or individuals who want to understand how their every day activities generate information that can be used against them and what to do about it. This book is designed for security professionals who create policies and oversee security management programs, and individuals who seek to increase their personal security at home and abroad. The content provides answers to four key questions: 1. Who are the threats?2. What are their targets?3. What are their hostile tactics?4. What countermeasures will stop them?Content includes the following: Operations Security, Critical Information, Open Source Information, Observation-Based Information, Web-Based Information, Imagery Intelligence, Communications Intelligence, Trash Intelligence, Social Engineering & Elicitation, Glossary of Terms, Acronyms.