This glossary of key information security terms has been extracted from NIST Federal Information Processing Standards (FIPS), Special Publication (SP) 800 series, NIST Interagency Report (NIST IR) series, and the Committee for National Security Systems Instruction (CNSSI) 4009 (Information Assurance Glossary). The terms included are not all inclusive of terms found in these publications, but are a subset of those most frequently used. The purpose of this glossary is to provide a central resource of definitions most commonly used in NIST and CNSS publications. Each entry in the glossary points to one or more source NIST or CNSS publications, and in addition, other supplemental sources where appropriate. As we are continually refreshing out publication site, terms included in the glossary come from out more recent publications.