Unique Identification Codes for Federal Contractors: DUNS Numbers and CAGE Codes [May 31, 2017] [open pdf - 781KB]
" The federal government uses a proprietary system, Dun & Bradstreet's (D&B's) Data Universal Numbering System (DUNS), to uniquely identify the entities with which it does business. At no cost to the applicant, D&B assigns a DUNS number-a nine-digit unique identification code-to prospective government contractors. (Businesses that are not would-be government contractors also may apply for a DUNS number.) The federal government's use of DUNS, however, is not limited to the identification numbers. D&B provides, pursuant to its contract with the General Services of Administration (GSA), 7 types of software products and 14 data products that enable the government to use DUNS for a variety of acquisition-related functions, such as paying contractors. Furthermore, approximately 80 data systems within the federal government contain DUNS information."
CRS Report for Congress, R44490
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html