North American Industry Classification System (NAICS) and Standard Industrial Classification (SIC) codes were created by the United States government to group similar companies into industries in order to collect, analyze, and share statistical data across various agencies. Just as library materials are grouped by Dewey Decimal or Library of Congress call numbers, companies are grouped into industries by SIC and NAICS codes. Many business databases allow searching by code which may help users find competitors and other industry information that would not be found in a keyword search.
Geographic areas defined by the U.S. Office of Management and Budget (OMB) are used by the Census Bureau and other organizations.
These resources are available online (click Connect to Full-Text).