Standard Industrial Classification (SIC) codes are four-digit numerical codes assigned by the U.S. government to business establishments to identify the primary purpose of the business. The classification records all economic activities. Companies use SIC codes to identify customers by industry code to identify competitors, public and private firms.

What Is A NAICS Code?
The North American Industry Classification System (NAICS) is used by businesses and governments for the classification of various businesses to measure the economic activity in United States, Canada, and Mexico. NAICS is 6-digit code system that is currently the standard code used to find out the individual business locations.