NAICS (North American Industry Classification System) code is used to classify businesses according to type of industry in Canada, Mexico and the United States. It was meant to replace the older SIC (Standard Industrial Classification) codes; however, certain government departments and agencies, such as the U.S. Securities and Exchange Commission (SEC), still use the SIC codes.
The North American Industry Classification System (NAICS) is the standard used since 1997 by Federal statistical agencies in classifying business establishments for the purpose of collecting, analyzing, and publishing statistical data related to the U.S. business economy.
This page has a link to a bridge between the NAICSs and SIC systems. The link to the page from OSHA allows the user to search the 1987 version SIC manual by keyword, to access descriptive information for a specified 2,3,4-digit SIC, and to examine the manual structure.