Complex sentence: Defense in Depth is an Information Assurance (IA) strategy where multiple layers of defense are placed through out an Information Technology (IT) system and addresses personnel, technology and operations for the duration of the system's lifecycle.
Split into simpler sentences: Defense in Depth is an Information Assurance (IA) strategy in which multiple layers of defense are placed throughout an Information Technology (IT) system. It addresses security vulnerabilities in personnel, technology and operations for the duration of the system's lifecycle.