It is an agency within the US Department of Commerce.  NIST has the lead responsibility for the development and issuance of security standards and guidelines for the US federal government, contractors, and the United States critical information infrastructure.  The NIST has published a series of publications in support of its risk management framework (RMF).  The RMF is a multi-tiered and structured methodology for creating a unified information security framework for the federal government in order to meet the vast array of requirements set forth in FISMA.