This book includes a glossary of common security terms that have been extracted from NIST Federal Information Processing Standards (FIPS), the Special Publication (SP) 800 series, NIST Interagency Reports (NISTIRs), and from the Committee for National Security Systems Instruction 4009 (CNSSI-4009). The glossary includes most of the terms in the NIST publications. It also contains nearly all of the terms and definitions from CNSSI-4009. The glossary provides a central resource of terms and definitions most commonly used in NIST information security publications and in CNSS information assurance publications.